Diagnosing death of fishes...

[nkthen]

Some of my fishes died and sometimes I hope to know why they die.

When some of my fishes die, they turn belly up and floated at the top.

Some of my fishes die and sink to the bottom of the tank.

Is there a difference in terms of their 'cause of death'?

[benny]

When fishes die, they lose they buoyance and will sink to the bottom. When decomposition starts, gas is formed internally and will cause the carcass to float.

This is by no means indicative of the cause of their death. There are other signs to look out for, such as physical damages/wounds. For internal bacterial/parasite problems, only an autopsy will yield clues. However, this can be quite difficult to perform on small fishes and without the aid of microscopes and a good reference on fish diseases.

Alternatively, put the dead fish(es) in the freezer immediately and take it to the vet in a ice box if you must know what caused the death of your fish(es).

Cheers,

[nkthen]

I see. I thought there is an indication of how they die by the 'location' of death.