Fish are Dying!

[FatherKing]

Hello, this is my first post here. I have a 20gal, fw tank, live planted. The tank is about 1.5 years old. Lots of water wisterial, anubius, amazon sword, java fern. As of the beginning of April (last month) I had 3 black kuhli loaches, 3 cory cats, 3 flying foxes, 2 chinese algae eaters, 2 oto cats, 3 fancy guppies, and a bamboo shrimp. One of the chinese algae eater is close to 6 inches and rather agressive. Most of the time he hides under a rock. Several weeks ago one of the guppies had babies so now I also have 8 fry in the tank (about 5 weeks old).

Over the past month i have been loosing a fish a week. 2 loaches (had them since the beginning) 1 flying fox (6 months old), 1 cory cat (since beginning of the tank). Today my bamboo shrimp (5 months) died. According to my API tester, my nitrates are high (between 40-80ppm). PH is 7.4. Ammonia 0ppm, Nitrite 0ppm.
Any advice????? I don't want to loose any more fish!

 

[alLexX]

look at the CAE's. they are normally very aggressive,especially to fish that look like them

 

[Mumma.of.two]

Welcome to AA!
First thing I'd recommended is some large water changes to get the nitrate down to 20ppm or less then some rehoming of your fish. CAEs are nasty, as you've found out, and do not belong in peaceful community tanks. They could very well be the culprits. Flying foxes do better alone. Three (now two) in the one tank is going to cause problems. I would rehome the CAE and at least one of the FF.
After that is done you can correct your schools. You'll need at least 5 cories and 5 kuhlis for them to be happy. I'd recommended adding another otto also.
Is this a high or long tank?

 

[FatherKing]

It's a 20 high. Regrettably, the big CAE has grown on me. but I'm reluctant to start a new tank just for him. Though I know that the kuhli's and corys are better in schools, they had been fine for well over a year. It's hard for me to believe that insufficient numbers was the cause there.

 

[Mumma.of.two]

A 20g high might cause a bit if a problem. Because its tall rather than long it doesn't have a very large foot print (horizontal swimming space). If it where me I'd rehome both FF as well as the CAE. A higher tank just doesn't have enough swimming space for a fish that size IMO. I have 4 SAE (about the same size and swimming habits) in a 17g high (same footprint) temporarily and I can see they are struggling.
Most pet stores take trade ins or adoptions.

 

[Holliesmum]

same problem

I have the same problem , my water tests are ok but i'm losing fish how what can i do with my cae ?