Four fish in three days

[Gryphon]

I have something going around in my tank and it is baffling me as to what it is.

I had 5 baby paradise fish in my 29 for grow out. I added 5 zebra danios hoping they would calm the two bigger paradise fish down a bit (and they did)

Weds. - Came home and found one of the danios dead, no signs of trauma or sickness.
Thurs. - Came home and had 1 paradise fish MIA. Looked healthy before, found no sign of it on the floor or in the tank. Later that evening found one of my danios slightly bloated, but swimming around and looking ok otherwise, thought I might have had a pregnant one. Two hours later it was even more bloated and swimming tilted to one side and finally died.
Fri - Came home everyone looked ok, noticed one of the bigger paradise fish had some slight paling around the mouth, nothing cottony or suggesting fungus. I noticed he was eating oddly, as if he was aiming beyond the food when he went to get some. Went to bed and when I woke up it was dead. His mouth was paler than the rest of the body, and the eyes looked cloudy but that could have been from death.

I checked the water parameters twice this week and everything checks good (Amm - 0, Nitrite - 0 Nitrate - 5) . As of now everyone else in the tank looks healthy, no signs of flashing or any other problems.

Any tips or ideas are appreciated!

 

[DMD123]

Is the tank newly set up? or has it been cycled?

The danios in many places are treated like feeder fish and many times are very unhealthy and not properly cared for. Did you get them from a source that would guaranty them? If so I would want replacement fish. The usual bring a body and water sample routine.

Not sure about the MIA fish... could the others have ate the body or is it possible it is stuck in a piece of decor?

 

[Gryphon]

Its a cycled tank, I've gone all over the inside of my tank and have found no sign of remains. I guess it jumped, although the biggest opening is only 1/4" by 1/2", so it would have had to have perfect aim lol.

Sadly though the Danios are past their "warranty" date. I wasn't worried too much about the cost of the fish, I'm more worried about something going on that I can treat. I'll just do the usual preventative measure, water changes until something obvious pops up.

 

[DMD123]

Maybe Dunecat got it. :cat:

 

[Gryphon]

Sadly another danio died. This time I noticed the middle of the body turned white like the mouth of the one paradise fish did. Stomach bloated, and he was floating upside down alive still when I found him. No sign of external fungus, the gills were a bit red, and no signs of injury.