Clown loach with red gills and gasping

[malfist]

I recently purchased 5 clown loaches to make a school in my tank. I left them in my quarantine tank for a week and then moved them to the big tank.

They've been in the big tank two or three weeks now, and they all seemed happy. However, when I got home today, I saw one was floating sideways or upside down, generally not something you see a healthy fish doing.

He's saying around the bubble wand too. His gills are very red, and he's gasping a lot. The other fish, including the other 4 clown loaches are doing fine.

What should I do to make him healthy?

Tank stats:
Size: 55 Gallon
Temp: 80 F
pH: 7.5
Ammonia: 0ppm
Nitrites: 0ppm
Nitrates: 20ppm
Test Kit: API Master
Chemicals Used in Tank: SeaChem Prime, SeaChem Flourish

Stocking: 3 Bala Sharks, 5 Clown Loaches, 1 (old) Black Moor, 1 (old) three stripe african glass catfish, 1 albino bristlenose pleco.

I did a 30% water change as soon as I saw the problem, so Nitrates should be lower, but they are under what would harm a fish. I'm warming up my 10 gallon quarantine tank to match the big tank's temp. Should I move the loach into the QT? Or would that be too stressful?

 

[librarygirl]

How big are these fish? Long-term, a 55 isn't going to be nearly large enough for 5 clowns, not even including your other fish. Were his gills red before or is this new? It could be an injury or infection; my first thought would have been ammonia or nitrite burns but the test results look good.

How is he doing now, any changes?

 

[malfist]

He died this evening after I moved him to the QT tank. But I have more information that may help others.

His gills were red, but the other clown loaches gills are red, but not quite so red. I don't think that was anything to worry about. And his breathing rate was only slightly high than a clown loach resting, so I think that was a false alarm.

That evening, he floated to the top of the tank, and stayed there. He seemed unable to sink. He also seemed to be in a permanent U shape, and didn't seem to be able to straighten himself out for more than a few seconds.

When he died, I dissected him to inspect him for a cause. I didn't see any signs of parasites or constipation, however he was very, very thin. Like he had starved to death. His swim bladder was completely full. My thoughts (and I've heard of this before), is a genetic deformity causing him to be unable to deflate his swim bladder. Although I don't know how the U shape fits into this puzzle.

The other clown loaches and fish in the tank continue to be fine. The largest clown loach is 3". I'm aware that I will eventually need a larger tank, and will either upgrade when I get to that point, or sell the fish and replace them with babies. The bala sharks would also need a larger tank. All the fish I did not designate as "old" I have had for less than three months.