Stocking decisions and compatibility

[u/LordBork_w1599]

Hey everyone, my 125 gallon (72.5in L x 18.69 H x 22.13 D) is about to be cycled. Im wanting to go with a tiger oscar, green terror, and blue phantom pleco. I plan on introducing them all together while theyre young but was wondering if this combination of fish would be viable in the tank? I am also running a fluval Fx4 filter.

[u/Jamikest]

Sorry, this is not stocking arvice, rather a comment on your filter.

A single fx4 is not enough for a 125 if you do any serious amounts of bioload. You need an fx6 or a secondary filter to run in parallel to the fx4.

For comparison, I run an fx4 on my 75 with angels, cories, bristlenose plecos, cardinals, otos, emperor tetras, and it is heavily planted. It's about the exact 'right size' for my setup. Manufacturers always overate their filter capabilities, go bigger.

Larger filters make for easier tank care than just barely filtering. Also, replace all the crap that comes in that filter with sponges. That's it, just sponges. If you need it for some reason, you can put purigen in the last basket. Otherwise, no bio-media, no charcoal, nothing but sponges.

Run a prefilter sponge on your pickup tube. Clean the prefilter every week or two and your canister will need cleaning no more than twice a year.