boesemani rainbow fish acting strange

Question
hi, i have 3male bosemani rainbows,1 7inch bgk knifefish,2 red rainbows[2inches],6pearl gouramis[2 inches],10 red zebras,and 2 high fin spotted catfish[3 inch} in a 25 gallon tank . 1  sponge filter,and a power filter fitted respectively .temp set at a const 27 deg Cenitgrade .one of my bosemani rainbows underwent a sudden loss in apetite,stared breathing fast and keeps itself to the upper parts of the tank .i noticed a small white patch in its tail but no discolouration or white spots. noticing this i did 2 daily 25% water changes. also sped up the oxygen flow a bit but no improvements noticeable . i fed them hikari discus pellets or tubifex worms occaisonally .all other fish are fine .pls suggest somethings but i dont want to increase the temp.ammonia reads zero!!!!!

Answer
Hello,

Debottam, please do not be angry if I give you honest advice.  I cannot lie to you...your fish are overcrowded to a serious level.

The aquarium you have is 25 gallons.  It can support no more than a few of the fish you have.

You have too many fish and if your ammonia is zero, then it is incorrect.

There is no possibility that a sponge filter can keep up with the waste being introduced into your water.

You can have only a few fish in a 25 gallon aquarium.

1" of fish per gallon, until they hit 3" and then it is 3" of fish per FIVE gallons.

This means you are way over quota for safety.

The white spot is probably cotton, a fungus, beginning because of severe overcrowding.  The water gets bacteria and that attacks the fish.

I'm so sorry to have to tell you, you need to increase your aquarium size to support that many fish, as soon as possible.

This is very unfair to their feelings.  They are breathing poop!

Also, a sponge filter is insufficient.

A filter rated to 25 gallons is insufficient.  You need one rated to 50, at least, and probably two of those with the amount of fish you keep.

Water changes need to be 25% every week to support this many fish.  

My advice:

Increase aquarium size.  At least a 75 gallon aquarium is required.

Increase filtration.  

Do water changes at a rate of 25% weekly.

Ammonia cannot possibly read zero.  If it does, it is because of recent water changes and/or a bad test kit that is aged.  They only have a 3 month shelf life.

Please take the Rainbow fish out and put it in a hospital environment.  Add 2 teaspoons of sea salt (marine salt) per gallon in his hospital tank to combat the fungus.  Keep his heat at 80F.

When you state you increased oxygen flow, did you use an actual oxygen tank or an air filter?  This water will not oxygenate without being changed.  The poop in it will keep it from holding oxygen.

Too many fish. :)

I am so sorry to be the bearer of bad news.  Please do not rate my expert advice low because I was honest with you.  I volunteer both, because I enjoy meeting people, and because I love animals.  I do not want to see fish in a tank that tiny with that many fish and I feel terrible for them.  Please, please do something right away to fix this issue.

Fast breathing, loss of appetite = ammonia and nitrates raised levels.  They are poisoned by their own water.

Please feel free to ask anymore questions and I will do my best to assist you.

Happy fish-keeping.

Renee