What Fish can I keep in my 55g aquarium?

You are actually fully stocked right now The goldfish need 20 gallons each and the pleco is good with the 15 gallons left over. I will caution you that the pleco will most likely start sucking on the goldfish which can cause massive infection. Goldfish should only be with similar goldfish.

The pleco can go as low as 70 degrees. The goldfish can`t tolerate temps above 72 long term. I would at least get it down to 72.

Your filtration needs a boost. The filter should be processing the entire tank volume 10x every hour. I am guessing you have an Aquaclear 70. if a filter is rated for a tank size of 50-70 gallons, count it as 50. You`d do well to add another. You also want lots of surface action for oxygenation. Bubblers are not aeration. They do almost nothing for that. They are more for aesthetic purposes.

Good luck!

I'm the person who asked the question but it wont let me update so I'll put it down here:

The rule is 20G for the 1'st goldfish and 10G for every other goldfish. So that's only 30g. A Goby

Pleco needs 10g as they max at ~3". So That's 40g. I still have 15g leftover. Fancy Goldfish

thrive better in warmer temps than colder temps. They do well up to 78F and I keep it at 76F.

Pleco's only suck the slime coat off of slim goldfish. Not egg shaped goldfish as they can't get

a hold. Air Stones are for oxygen. I don't know what your talking about Sarah. They agitate the

surface creating more oxygen. It's not called an Air Pump for no reason. I recommend if you don't

know what your talking about, don't answer at all Sarah.