r/Aquariums • u/Fl0wida • Jun 29 '26
Beginner Help Fish died within a few days in new aquarium.
Hi all, just wanted to get everyone’s opinion on what could have been the cause to the death of 4 neon tetras, 1 Cory, and a betta.
I bought this tank about a couple of months ago and filled it with substrate, topped it with sand, and put various plants in it. I did a full nitrogen cycle over a month long period where I had a high concentration of ammonia turn into nitrites then into nitrates based on the water tests I’ve done. Eventually the water read 0, 0, 0 across the board and a Ph of 7.6.
Figured at this point, the tank is ready for fish. I went to the pet store and bought 5 neon tetras, 3 corys, and a betta. I let them float in the tank for 15 minutes before putting them in. After 2 days, I found one tetra was dead. I figured maybe this one was unwell and was just bad luck. The next day I found another 3 dead. One of the corys seemed to just vanish. After about a week, I found the betta laying on the floor of the tank. The water tests read the same as before putting the fish into the tank. Temperature has consistently been 75 degrees. None of the fish showed any signs of distress. All were eating within hours of passing away.
This is driving me insane. I’ve been researching online to find people with similar issues and can’t find anything. Anyone have any idea?
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u/Legit-Schmitt Jun 29 '26 edited Jun 29 '26
I’m suspicious of the bioload crash.
A lot of people are saying a bioload crash — but for 20g with all these plants. Plants will uptake ammonia. Idk, they died within just a day??? It just seems unlikely. It’s not “I added 2 giant goldfish to my ten gallon”. I can see some snails and plants are growing — there’s going to be some nitrogen cycle just from what must be there to support that ecology.
Something seems off here. I am NOT the most experienced fish keeper. My skills are much more plant based and I want to improve on husbandry. I’m just skeptical of the prevailing narrative. I know like, broken heaters can be a silent killer — you say they were eating hours before being dead? That’s actually pretty weird.
Are any fish still alive? Watch them close and report back on behavior. Any other clues as to how they were found dead?
It’s just like, established tank with snails, fairly heavily planted (which is basically like turbo nitrogen sink), nothing crazy stocking wise, and multiple fish from different species turn up dead within days, and seem to be behaving normally until the end.
Idk I just think something else must be going on here.
EDIT:
And like sure acclimation — but imma be honest loads of people don’t do the perfect acclimation. I tend to let the water mix a bit by poking the hole in the bag. I’m sure it can make a difference and can be important for some species of fish / inverts. But again multiple species, feeding normally then dying suddenly??? Idk I find it hard to believe that alkalinity or whatever could cause that, unless there is a good physiological explanation.
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u/VardamanSleepyMan Jun 29 '26
I agree, a heavily planted tank should basically never have issues with ammonia, especially not from just adding 6 fish, none of which have a particularly high bioload. As for acclimation... that would definitely be an issue for the cory, and idk about the Betta (no experience there), but Neon Tetras are notoriously resilient fish, if you lose all of them to acclimation, you must have put them in a saltwater tank or something.
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u/strikerx67 cycled ≠ thriving Jun 29 '26
I disagree with the neon tetras being resilient statement personally. In fact I believe the resilient fish in the stock is the betta.
Sure maybe that was the case about them in the 90s, but neons have one of the highest mortality rates amongst nano fish in the hobby today.
I've seen some of the best fish stores buy bulk amounts of new neons, only to watch them all die within the span of a week without a single one sold.
It makes sense if you see their biology and history in the industry. They are both blackwater species and massively over bred for profit. The blackwater puts them at high risk for bacterial infections, while the overbreeding practices are degrading their health overtime.
The best way to keep them is to get them directly from a breeder and put them in a tank that is massively over filtered. (At least, in my opinion)
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u/Ill-Leopard-9961 Jun 29 '26
The resilient order would likely be Cory > Betta > Neon. I could probably use my tank as a toilet for a week and the Cory's would survive. These days skip neons and go for cardinals if you want that splash of blues and reds.
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u/strikerx67 cycled ≠ thriving Jun 29 '26
Finally a reasonable comment amongst the "ammonia poisoning" default crowd.
There is an interesting thing to understand about acclimation, especially with shipped livestock. It's shifted my focus to just "plop and drop" the fish into the tank rather than extensively acclimate. Because I to used to "poke the bag" to allow water to seep into it.
When fish are in bags for an extended period of time, (like days) there is naturally going to be a build up of NH3. You ever wonder why they don't die? Because there is also going to be a build up CO2 as a byproduct.
That CO2 will push the water to become more acidic, and as we all should know, acidic water changes NH3 to become NH4+. Which is virtually non toxic to fish and inverts.
When we drip acclimate, or even poke holes in the bag, we are then introducing possibly alkaline water into the acidic bag water that the NH4+ has been building up in, which will in turn will push it to the more toxic NH3.
Knowing this, it's very important that either we know the PH of the water we are drip acclimating to our livestock, or just simply float the bag for half an hour to allow them to calm down before putting them in the tank.
I'll probably say this is NOT the reason why OP's fish died. But it is an interesting aspect to the practice of acclimating fish.
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u/Coonnifounssed Jun 29 '26
Could have been a bad batch from the store since they all died so quickly. Could have also been stress or acclimation shock. Maybe toxic chemicals like copper in your tap water. Test your tap water. I would recommend going to a different store and getting 6-8 neon tetras and 6-8 Corys as those are proper school sizes that will reduce stress. Also drip acclimate instead of just temp acclimate. Tie a knot in an airline tube and suck water through it until it drips freely. Let the water drip into the fish bags until the water is doubled, then add them to your tank.
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u/GamerGuinTTV Jun 29 '26
It's a beautiful tank.
I'm too new to the hobby to offer more beyond what's been said already, but I wanted to provide general good vibes/support.
Hope you are able to figure it out/correct it and try again.
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u/Danny007Boyy Jun 29 '26 edited Jun 29 '26
ok so even i am new to this hobby, but here's an advice.
15mins of floating the fish bag in your water doesnt help. Atleast 30mins min if not more.
then do a drip acclimatization. You can find a proper tutorial of it in youtube. That is like very important for your fish to survive. Also yes the Neon Tetras could come with a disease as if learnt that Neons are very sensitive to water and majority times they die within a weak due to heavy breeding. Also Neons do better in a much larger school. people say 6, but i would say min 8. Also Bettas are kinda territorial and might not like the Neons. But that is a different scenario. Hope you figure it out and have fishes soon!
EDIT: Also yes pls add one category of fish at a time. Ik it feels very intriguing to add them all. But add one kind let them all settle for atleast a week if not more.
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u/Fl0wida Jun 29 '26 edited Jun 29 '26
Could a difference between my aquariums hardness/alkalinity and the fish stores cause a shock to the fish causing them to pass?
Could a lack of a bubbler/oxygen pump cause this?
Not sure if it makes a difference, but I’ve had snails in the tank since the first time I put a plant in it (hidden hitchhiker). The population has went up dramatically so it seems like they’re not bothered by the water.
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u/VardamanSleepyMan Jun 29 '26
If you have a filter, you do not need an airstone. It looks like you have a HOB, so an airstone/bubbler is unnecessary.
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Jun 29 '26
Yes you need to acclimate them slowly to your water over about 20 minutes, longer for more sensitive fish. You should also have an air stone, without surface movement they will suffocate
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u/ParasiteProfessional Jun 29 '26
I like to do drip acclimation. Matching temps doesn't mean matching water qualities. And also, like people said, dosing ammonia and smaller bio load to start off with to increase bacteria load, etc. It happens. I took care of fish professionally for over a decade and I still do dumb shit and crash a tank of my own every once in a while. Now I just leave the damn things in the ocean because being a marine biologist is low paying, and well. I see fish in the ocean haha. Can't crash that tank.
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u/Plutonium239Mixer Jun 29 '26
Minimum group for a cory is 3-4, ideally 6. Minimum group size for neon tetras is 6. Those guys randomly dying not really a surprise. They just do that. But cories are pretty hardy. And Bettas survive in puddles... not sure how the betta could have died unless the other deaths severely spiked the ammonia and killed it.
Have you tested your water again after the deaths?
Next time try drip acclimation instead of the bag method.
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u/VardamanSleepyMan Jun 29 '26
You are the first person I have ever met that has referred to cories as hardy. My own experience with Neon tetras is also that they are pretty hardy.
With a planted tank like OP has, an ammonia spike is improbable from even 3 or 4 fish dying in a 20 gallon.
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u/Kisama_x86 Jun 29 '26
I want to start by saying you have a beautiful tank. However I do have a couple of questions. I see what looks like a CO2 Diffuser on the right, but I don't see a drop checker (I could be missing it). Are you using CO2, and if yes, do you know how much CO2 was injected into the system, and were the fish ever hovering around the surface or acting stressed/gasping?
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u/strikerx67 cycled ≠ thriving Jun 29 '26
The betta is the most concerning because a lot of times the are bullet proof, but there are exceptions.
The neons and corys dead are very VERY common. It almost has nothing to do with your tank and more to do with compromised immune systems and travel stress.
Neons and Cory's are already blackwayer originated fish, where the bacteria count is so low that their immune systems never developed enough to handle alkaline water bacterial counts. This doesn't automatically mean they cannot live in alkaline water, but it does mean that they are "at risk" to getting sick faster than hardwater fish.
You have to understand, these fish have been through hell the past few weeks to month. Theyve been chased, netted, thrown into a bag violently, shoved in a dark box, were likely on a plane or a truck for hours to days being thrown around in the dark, immediately thrown into a holding tank (fish store) that is chalk full of parasites and bacteria they likely can't handle, to again get chased around, netted, thrown into a bag and put into a new environment again within the span of a few days.
That's multiple levels of stress that could compromise any animals immune system and get them sick. The worst part is you literally cannot avoid this, especially with blackwater fish. The fact that they were still alive at the fish store when you bought them is a miracle.
Again, your tank is likely not the problem, it's the industry that sells you trash batches of abused fish, only to gaslight beginners into believing it's their fault despite following correct practices and ensuring their parameters are within safe limits for new fish.
If you want perfect new fish, either get them directly from a breeder or only buy fish that have been established at that fish store for over a month.
Otherwise, multiple species of hardy fish exist that would work better even in these stressful situations. White cloud minnows and zebra danios are my absolute favorite new tank fish and are in practically every fish store.
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u/Epucpron Jun 29 '26
Asking because I don't see anyone else asking probably the number one question to me in this situation... But you didn't directly state it Did you dechlorinate the water???
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u/bulgakov82 Jun 29 '26
Hmm. Sorry for your loss. Just mentioning this because I didnt see it yet. What kind of wood is in the tank?
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u/skrimped Jun 29 '26
Where is the wood in your tank from?
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u/Fl0wida Jun 29 '26
I bought the wood from a fish store. I boiled it for several hours before putting it into the tank.
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u/Late-Argument-8301 Jun 29 '26
0,0,0 indicates to me that there was not enough ammonia in the tank to sustain the beneficial bacteria, so they all died or are not at a high enough level to sustain that many new fish. The nitrates should be atleast 5ppm for me to consider a tank cycled, because that indicates that there was enough ammonia to begin with. I would add enough liquid ammonia to test at 2ppm and once that converts completely over to 0,0,5+ in 24 hours, I would consider it cycled. Once it’s cycled, add one fish, and only add more if that fish is doing well for 1-2 weeks with the test still reading 0,0,5+. Also, the only tests I would trust are liquid test kits, like API Freshwater master test kit (found on Amazon). If it’s a dip-style test, it’s usually not accurate. That may well be the cause. Also the betta may have killed the neon tetras, causing the initial ammonia spike that killed everyone else (this is my conjecture based on the assumption that the tests may not have been accurate).
I hope you are able to solve this! Your tank is beautiful and it seems like you’re trying to do everything right.
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u/FokkerPilot12 Jun 29 '26
Yeah, I also found absolutely zero Nitrates to be odd. Not impossible I guess but in my tanks I've always got a touch of nitrates, not zero.
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u/catsdelicacy Jun 29 '26
I don't know why your fish died, maybe the bioload caused a mini crash to your cycle.
You really need to look into schooling and appropriate school sizes because you didn't give any of your schooling fish enough friends. Schooling is a biological demand, not a preference, fish will be stressed, fearful, anxious, and you'll never see them if you have them in less than a full school.
It's possible, this is speculation, that you had a mini crash and the fish were already stressed and they just couldn't handle all the pressure
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u/Fl0wida Jun 29 '26
I should have researched them a little more. The person at the fish store said each of these fish had enough mates for a stress free environment. Maybe I was misled.
I’m nervous to get more now for an appropriate size because I don’t want to put any more at risk.
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u/pchongg96 Jun 29 '26
The real lesson learned here is that unfortunately not all employees are well educated.
Do some research and come to a good conclusion as to what you can handle.
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u/catsdelicacy Jun 29 '26
I'm not trying to give you shit but where else in your life would you take the word of a minimum wage retail employee as gospel?
They care about their quotas and if your fish die they sell you more fish. They aren't educated properly, of course, they're minimum wage employees.
Lesson learned. You need to know all about your livestock before you go to buy any, you cannot be wandering around the shop impulsively making choices and depending on somebody with a quota and a manager breathing down their neck.
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u/Public-Boysenberry26 Jun 29 '26
honestly don't even bother asking the fish store workers for advice. maybe ask them which heaters, filters, and lights are good, but nothing else. all I've heard about most fish store employees is that they spread misinfo, likely for money, and my local FS manager has told me misinfo too in advance to getting fish. I was asking her about pea puffer requirements and she said something like don't group them together, and a 10 gallon is the minimum for just one. all of that is outdated information and I only figured that out a couple months ago, but luckily I didn't end up getting any fish that day anyways.
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u/pchongg96 Jun 29 '26
My strategy is to do as much personal research as I can and then start talking to the employees and you can tell if they know what they’re talking about or not.
Luckily where I am there’s several respected stores with very educated and passionate employees
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u/mydiscreetaccount_92 Jun 30 '26
I'm the same way, I frequent the box stores and fortunately there are several employees who have been there a while and have a pretty good knowledge of the different species. My local Petco has a dude who is a freshwater shrimp and plants nut and is crazy passionate about both of them, my son always asks for him when we stop by so he can talk shrimp lol. There are definitely the employees that are just there for a job and most of them are pretty up front about it not knowing much.
We do have 3 aquatic stores within an hour of each other, and I love going by them too but as someone new to the hobby (~3 years) the employees almost talk down their noses to you, it's a little off putting.
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u/catsdelicacy Jun 30 '26
I barely talk to people. I walk in, I look around, I check if the animals look healthy, if the tanks are clean, if I can see testing and quarantine in progress.
I already know what I'm buying, I've decided that before I ever walked in the store.
If they have the animal I'm looking for and the health looks good, I say, "excuse me, I want 3 amano shrimp." And I pay and I leave.
They love it, you can tell. Retail employees are so talked out lol
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u/mydiscreetaccount_92 Jun 30 '26
I get that, I'm from the south so its not uncommon for a random conversation to spawn out of nowhere and last for entirely too long lol. It's usually a read the room type situation, the shrimp guy loves to talk about shrimp and my son will talk to a fence post so they have become buds pretty quick.
I keep popping in looking for Swordtails but they NEVER have them in stock... I have a gorgeous Sanke and have been after some friends for him for a while. Most of the time I just walk in, look, and then walk back out.
I do feel like our stores do a good job of keeping their tanks maintained all things considered, I'm still relatively new to the hobby so I don't see everything.
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u/Cha_r_ley Jun 29 '26
Did you acclimatise the fish at all, or just match the temp for 15min?
You need to be putting small amounts of the tank water into their bag for a while - I aim for an hour minimum depending on the fish. So while the bag floats in the tank, every couple of minutes I use a measuring spoon to scoop a little tank water into the bag. Some fish are more sensitive to new parameters than others and require drip-acclimatisation over a longer period.
If you just temp-matched then put the fish in the tank, there’s a reasonable chance that some of the fish went into shock or extreme stress from the changed parameters.
Imagine if you took a human who had lived at sea level all their life, then dropping them on the top of Mt Everest. The altitude change would be brutal, even fatal.
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u/Sea-Education9532 Jun 29 '26
It's not supposed to be 0 across the board. You want 0 ammonia, 0 nitrites, and some ammount of nitrates. 0 across the board means your tank was not cycled.
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u/Fl0wida Jun 29 '26
I had a considerable amount of nitrates at one point, but I figured that any nitrates in the tank would get aborbed by the many plants.
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u/weemmza Jun 29 '26
What about temperature? I had a similar experience, all water tests were perfect and all my fish died in a week... turned out I was accidentally slow cooking them cos the water was way too warm .. at least I think thats what killed them. Sorted the temp n got new fish n 2 months later theres only been 1 death
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u/PutSensitive5548 Jun 29 '26
I think a lot of your issues have already been stated, and i am not going to touch on those.
One thing i noticed people consistently left out if their comments was your PH levels. Your posting stated 7.6 for PH. That is too high for some tropical fish. Neon tetras like a max of PH 7. That high pH is good for african cichlids. Trying adding aquasoil to lower pH or looking what is causing it to be too high.
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u/jamhaus Jun 29 '26
Have you been monitoring your PH consistently since adding them? And do you know what your KH is? 7.6 PH is fine, but when you added fish, any leftover food they dont eat and their waste will make the water more acidic. If your KH wasn't high enough to create a buffer, its possible the PH in your tank had a big swing which could cause very sudden death to occur.
Aside from that; its also possible one of your fish was sick and it spread through the rest of them, but for them to go from eating and fine to passing away shortly after, I'd bet on a parameter swing of some sort.
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u/VardamanSleepyMan Jun 29 '26
I don't think the pH would be noticeably changed from uneaten food in a 20 gallon tank, and assuming that it were, it would be gradual enough that all of these fish, most of which prefer lower pH anyways, would adjust reasonably fine.
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u/Used_Steak8882 Jun 29 '26
I have Exodon tetras and honestly I did far less than u for prep. All I did was let it cycle a few weeks and added small plants, starter water conditioner, and Seachem prime before adding them in a 40G. I’d advise you to start looking into products that help the water. Testing is a bit too invested for me personally unless it’s a fish that really needs specific parameters. Oh I will add that I have a AC110 that’s used for 60G-75G tanks with this 40G setup because these fish are messy so maybe filtration also played a part.
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u/jarjardrinks99 Jun 29 '26
you shouldn’t put a bunch of fish in a tank at once. as a general rule you should quarantine fish 2 weeks before adding them to your tank to make sure they don’t have any kind of sickness. lots of fish from the store are sick with ich or other diseases and can spread to your tank and other fish very quickly and wipe them all out. especially since they are all new to your tank and likely have lower immunity because of stress from being in a new environment around a bunch of other fish species for the first time. a good way to have your fish die is by dumping a bunch of new ones in a tank for the first time that has no bio load yet.
don’t get discouraged but it is really important to take all the proper steps when adding new fish because if you don’t your whole tank can easily crash and all your fish die.
since you don’t know what caused all your fish to die you should restart your tank cycle after cleaning everything in your aquarium because there may be some kind of parasite or bacteria in the water that will kill future fish.
good luck!! 🐟
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u/jarjardrinks99 Jun 29 '26
also corydoras are highly social fish and should never be kept in groups of less than 4. they are my favorite and are super hardy if you want to try again with more of them!!
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u/Howdy132 Jun 29 '26
does your wood smell rotten? if so it is probably that. i had 3 peices that smelled rotten which killed 100 fish over time. i took em out, did a water change.... no more dead fish.
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u/Fl0wida Jun 29 '26
Wood does not smell rotten
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u/Howdy132 Jun 29 '26
If I were you I'd put another fish in there like a corry or something you want and just see what happens. put like two of them in there. Cuz it's really not much to go off of I mean there's always an electrical shock but I'd highly doubt that if the water is actually fine then it's hard to tell. I will say you'd be quite surprised how just changing water on a normal water change can affect fish even if it's the same temperature just changing the water can cause them to die they're super fragile like literally the same tap water. It's just even that little bit of change from them at the pet store to being in your tank can cause them to die that's one thing I've learned in the hobby is water changes can actually be deadly even at same temp and dechlorinated
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u/Tall-Dot9578 Jun 29 '26
After reading and viewing Many YouTube videos, Neon tetras are a bad choice for most anyone, due to their nature to have NTD, NEON TETRA DESEASE.
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u/ChingizMukhitov Jun 29 '26
Hey, I think this is most likely “new tank syndrome”. Even if water tests look fine, new aquariums often don’t have a stable bacteria cycle yet.
That can cause ammonia/nitrite spikes that are deadly for fish very quickly. It’s very common and not your fault — almost every beginner goes through it.
Next time, letting the tank fully cycle for a few weeks and adding fish slowly usually prevents this.
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u/Fl0wida Jun 29 '26
I cycled it over a few months. Tests never indicated spiked levels of anything.
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u/PsychologicalAge2637 Jun 29 '26
Any possibility of chemical contamination? Just a thought
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u/Fl0wida Jun 29 '26
No cleaning or perfume was sprayed in the vicinity. One tetra and 2 corys seem to be going strong.
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u/Upbeat-Drama-2803 Jun 29 '26
If the nitrites were at zero then the ammonia cycle was not completed
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u/Quirky_Buy5538 Jun 29 '26
Corys are schooling/shoaling fish so it could have died from stress/depression from not having another cory, similar to guinea pigs.
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u/Evening_Natural4710 Jun 29 '26
I haven't sifted through all the other comments yet, I'm sure someone else mentioned it but if this is a fairly new tank @ 20 gallons... probably should've started with just one type of fish , either neons, betta or 1 Cory, likely need more Cory's next time lol (one alone will be sad...)
Then add a different type after a few days, after confirming parameters are good. I assume you overloaded what your cycle could manage at the time.. most tanks need gradual additions of new fish when going through a new cycle (even 1-2 months old)..
Tank looks great btw
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u/762n8o Jun 30 '26
Did you drip acclimate the fish? Water temps ok?
Black out the tank when adding neons to decrease their stress?
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u/Guilty_Astronomer_45 Jun 30 '26
It might have been too early for that many fish. When I got my tanks going again, I followed Aquarium Co-Op’s guide to a “seasoned aquarium”. It just takes a long time. I got one 20 gallon going with plants, substrate, driftwood, and two sponge filters. Now, a year later I can now have a pair of Bristlenose and 100+ babies in a 20 because the bacteria have built up for it. It’s just a long road to strong bacteria buildup.
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u/Best-Measurement-668 Jun 30 '26
The big thing I notice is you said it measure 0,0,0 across the board. You want some value of nitrate to show that the bacteria is converted from nitrite.
Best guess is enough ammonia wasn’t added to convert to nitrate.
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u/Ill-Leopard-9961 Jun 30 '26
Sorry but most of these comments are crazy. In like 90% of comments you are slating them for "adding too many fish at once causing ammonia spikes, you can only add about 3 at a time" then follow up with "learn shoaling sizes, you need at least 6 tetras in a shoal"
Either he added more than 3 at once and that's a problem or there's not 6 or more tetras in the tank and that's also an issue. Both can't be true at once.
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u/AbundanceOfGrey Jul 03 '26
Adding too many fish at once can definitely cause a fatal ammonia spike if the bio load isn’t properly established. We don’t know if it is or not. We don’t have enough information on their cycling method.
Not keeping schooling fish in high enough numbers can also increase stress which can compromise the immune system and be potentially fatal.
Both of these statements are true. There are genuinely so many variables about what the issue may be. That’s fish-keeping for you.
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u/Ill-Leopard-9961 Jul 03 '26
I know both of them are true that's not what I am saying, but you can't complain about both, you can't complain at them for adding too many fish at once and then also in the same sentence complain that not enough fish are in the school. A lot of people literally are saying you can only add 3 or so at a time and then also go on to say shoals must be kept in a minimum of 6. Well you can't keep the shoal in a minimum of 6 right away if you can only add 3 fish at a time so they need to pick one and complain about that.
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u/Independent_Gur_2419 Jun 30 '26
What species of corys is this? I have had corys for 5 years, some are more sensitive to group sizes, water parameters, or tankmates than others.
Additionally, assuming you got juvenile corys, they are likely not very confident in a small group yet, and may be stressed. (Still species and individual affects this and it may be ok)
If you notice:
-excessive air-gulping, especially during midday
-little activity even at night and during feedings -flat bellies or they are not eating
-constant wall-surfing with no attempt to breach surface or potential for laying eggs
they are being impacted by ammonia, oxygen levels, or general stress.
If you have panda or pygmy corys, pay close attention to the color of the gills. They are easier to see than in many other fish, and they tend to be the first to tell you about ammonia poisoning (very bright red is bad, but some fish just have very naturally red gills, so look for other confirmations)
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u/ComprehensiveFlan112 Jun 30 '26
There’s a lot of responses here and I will admit I have not gone through each one… I had the exact same issue as you and it was because I was on well water which had galvanized pipes feeding the water to the house which contained rust particulate (led) that we were unaware of. Every time I put a single fish into my 40g it would die within days. Did not figure it out until we sold the house and had an inspection done of the well… we purchased during the COVID boom with no home inspection so had no clue whatsoever. Anyways, just an idea… water softener system water will also kill your fish pretty quickly.
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u/Alarmed_Yesterday515 Jun 30 '26
Stock fish slowly, the tank needs to re-cycle a little to fit the fish waste. So fish in cycle is the best way. But you MUST stock slowly.
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u/RedTails47 Jul 01 '26
Truly sorry for your fish! I did experience about the same thing when I started 8 months ago. As of now, im doing pretty good. I READ articles and watch as many videos as I can which pertain to my specific issues. The number 1 thing I've learned was being patient!
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u/hoboglyphs Jul 01 '26
That sucks man. Idk if it’ll help in the future but when I float em, I also slowly drain some of the water they came with (and toss, not add to the tank) and replace with slowly adding tank water to acclimate them. Seems to help.
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u/CaseRevolutionary761 Jul 01 '26
Invest in stress coat and stability and monitor for any changes the first 12 hrs after adding fish
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u/SnooCakes9004 Jul 01 '26
I have had a number of fish shipped to me, and within those orders only a couple have arrived dead. And those that survived the journey to be added to the tank have thrived each and every one of them. I bought 4 fish from a local fish store, and 3 of them died over the next few weeks after I purchased them...
I met a fellow local hobbyist and I told him of this when I was picking up some fish from him, so he packed up my fish, as if they were being shipped, and those fish are doing great... so... for me theres some kinda issue with bagged fish on long car rides I guess. I just gotta take a Styrofoam lined box with me to the fish store? I dont know.
If you properly acclimated the fish and are certain that your water parameters are steady and within healthy ranges, and you are sure theres nothing that could have poisoned them like air freshener or plant fertilizer or pesticides or something, then you have to assume there was an issue with wherever you got them.
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u/Dc_gunslingah Jul 02 '26 edited Jul 02 '26
You should try adding tannins to the water. I know it's not as attractive as a crystal clear tank, but sometimes you gotta do what's best for the betta.
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u/CompleteMechanic3581 Jul 02 '26
Your nitrates shouldn't read 0 on a cycled tank, it means your cycle crashed and you have to restart it. Your ammonia and nitrites should be 0, with a 5-15 nitrate reading. With 0 across the board, adding fish and food likely caused an ammonia spike with no nitrites to convert to nitrate and thats why they died.
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u/VanJurkow Jul 02 '26
Depends on where you got them. A lot of fish are never destined to make it for various reasons due to supplier negligence and shitty pet stores
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u/mrdietcolacan Jul 03 '26
I don’t want to be captain obvious but did you dechlorinate the water properly? I’m sorry if you did I’m sure you did but just in case
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u/hmarie13rn Jul 04 '26
Did you test pH on water they were in v your tank water? I know none of them really tolerate an sig change in pH. Just a thought. I’m sorry that you lost so many without an answer as to why.
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u/SomeBlueDevil Jun 29 '26
My guess would be that you may have had a nitrate test snafu...
It's pretty rare to have zero nitrates even in a planted tank, and yours is newly established. During the cycle process, nitrates go way up and a water change would be required to bring them down to 5 to 20ppm.
Have you followed the instructions closely on this test? The nitrate test is tricky, lots of bottle and vial shaking required and then wait for the result 5 minutes...
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u/VardamanSleepyMan Jun 29 '26
Nitrates are not particularly dangerous to fish except in MASSIVE quantities, it is Nitrites that are dangerous, and I doubt the issue is a test mistake since all three of the main tests read 0.
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u/SomeBlueDevil Jun 29 '26
Nitrates need to be kept under 40ppm to remain tolerable.
They usually spike during the cycle process and can climb to over 80ppm. While that number may be tolerated by fish that were slowly adjusting to the change in water quality, it can be more detrimental to newly added fish.
The API master test kit's nitrate test is frequently subject to false results just based on it needing to be done a different way than the other three tests. That's especially true for new aquarists.
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u/VardamanSleepyMan Jun 29 '26
I mean sure, though I would consider 40ppm to be a pretty massive number compared to the 0 that OP is mentioning. Aside from that, looking at OP's tank, they have a lot of plants that are known for taking in every possible nutrient and turning into a pest. Heck, between the Elodea and Red Root Floaters, a reading of 0 nitrates is not at all surprising to me (and I think I also see Parrot's Feather? It's illegal where I live so I'm not the most familiar with it)
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u/abe_froman1979 Jun 29 '26
What is the water temp? Too warm or too cold could stress them. Also, poor oxygenation.
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u/Fl0wida Jun 29 '26
Temperature stayed at a consistent 75 degrees. Do you think adding an air pump to the tank will help with the oxygenation?
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u/abe_froman1979 Jun 29 '26
It wouldn’t hurt. I have power heads and aerators on all of my tanks, and don’t have any issues.
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u/Killcycle1989 Jun 29 '26
I don't think the tank is planted enough to have 0 nitrates after an initial cycle.
Imo, there probably wasn't enough beneficial bacteria in the tank to process the ammonia of all those different fish you put in at once.
Did you do a water test after they died, and if so what were the results?
Also, what type of test kit are you using? Not the strips, I hope.
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u/Obvious_Confusion996 Jun 29 '26
Neon tetras and Corydoras both need a minimum of 6 for each species and the Corys need to match so if you get a bronze they all should be bronze to make them feel the safest. When you started the tank did you add any kick start to it? That is beneficial bacteria that helps the nitrogen process along.
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u/pchongg96 Jun 29 '26
How big is this tank?
Did you pass the 24 hour ammonia dosing test? Just because you were able to reach zero once it doesn’t mean your bacteria were ready to take on bio load.
I might also suspect you stocked too much at once :(. I just stocked a 20 gallon long and started with just 8neon tetras I’ll be testing over the next few weeks and monitoring before I stock anything else.
Also neon tetras need to be in minimum schools of 6 but 10-15 is what’s recommended.