fish stop eating then die

[james99]

I've had three fish die so far. They stop eating then die within a few days. Before this they eat normal and look normal. So far I've lost 2 peacocks and just scooped my large compressicep out. He was the tank boss and the largest. He ate when I fed them yesterday, I skip feeding on Wednesday since it water change day. I'm thinking its an internal problem, im starting metro soaked food tomorrow, even though I haven't seen any white stringy poop yet. I did have a bloat out break about 6 months ago. Here are my tank stats.

125 gallon set up 3-4 years
0 ammonia/nitrite
40 nitrate, no water change yet
Weekly 50% WC, sometimes 2x weekly
78 degrees
Fx5/xp3 filter
18 male haps and peacocks ranging 4"-10"
NLS and occational zucchini
No new additions in months

 

[Joecool44]

Could be anything could be parasites, I would check ur food and see if it's good it could be soiled

 

[james99]

I share the food among 3 tanks, this is the only one with a problem.

 

[Lepisosteus]

Look at the bellies of the fish, if they look thin then it could be internal parasites. If so use metrodazole (spelling may be wrong).

 

[james99]

The fish that died look good, there is one peacock that is sunken in, that's what led me to my original idea. The metro didn't come in with the stores order today, so I have to order my own.