Help, my tropical fish keep dying!

Question

Hello,

I have had a 190 litre tropical fish tank for 6 months, have set it up properally and have been adding fish slowly. The last fish I added are 3 angel fish, two weeks ago, one of these has died already and another is swimming really slowly and looks like the current is blowing it more than it swimming. I have also lost a male guppy. All the fish are relatively easy to keep and I have checked the levels of nitrate, nitrite, ammonia and ph and they are all fine. the temp is running at about 25. I also have live plants in the tank for oxygen.

There is no outward signs of any illness, no white spot, no fungus, no finrot. If anything the fish could be gasping (but how would i tell?) and possibly more sluggish. I did put a sloution in there for the treatment of all illnsses that turned the water blue, used as reccomended for 7 days on alternate days. But I worry if it may harm the fish if nothing is wrong.

Any ideas why they may be dying? Help

Answer 1

What this sounds like to me is that maybe your oxygen levels are low and unable to support the amount of fish you have in your tank. Live plants do add oxygen but if you have a large number of fish you are going to need to put an aerator in their to help support your fish respiration. When you say 25 degrees I am assuming you mean celsius (since you are using liters) and this is a healthy range for most tropical species. I wouldn't put in any medication as this may harm the fish. I would recommend holding off any treatment until you start to notice a sign of disease.

Answer 2

Angel fish are very aggressive.

They may be attacking your other fish.

That is the only thing I can think of.

I had Angel fish and they killed off my other fish, chasing them and then biting at them.

:-)

Answer 3

Overcrowding

lack of oxygen

Too much food

Filter inefficient

Temperature wrong