Which one doesn't belong

[southernbelle]

I've had my 55 gal. planted aquarium for about 3 years now. I thought I had a good mixture of fish but over the past 6 months something has changed. Currently I have 1 bala, 4 golden barbs, 2 swordtails, 2 black mollies, 3 bloodfin tetras, 1 tiger barb, 1 cory cat, 1 chocolate pleco and 1 regular pleco. I also have 2 bamboo shrimp and 2 yoyo loaches.

When I first started out I had 6 swordtail, 6 neon tetra, 6 glofish, 6 bloodfin tetra, 1 bala, 1 cory cat, 6 tiger barbs, 4 golden barbs, 1 pleco, 2 yoyo.

I slowly added as fish would die but now I have something that is killing the fish. I put in 4 bamboo shrimp which is down to 2. My healthy breeding swordtails no longer breed and I am down to 2. If I add any more swordtails or tetras they just die. I tried to add mollies...all but one died and the only other one I have started as a baby. Tiger barbs were doing well....down to one. The golden barbs...well those just won't die. Plecos (both chocolate and common), cory cat and 2 yoyo loaches are healthy and active.

So please can anyone give me any idea who is eating my swordtails, tetras and bamboo shrimp. It is very frustrating at this point and I don't want to put any more fish in until i know why they are getting killed.

[Oscar_freak12321]

Hmm...what are yuor water params? It might not be your fish. I don't see any real threats, but balas get a little big for a 55. All of your fish aren't aggressive, so I'm leaning on the water being the problem.

[southernbelle]

My bala is only about 5 inches right now. I know they get big but so far it's reasonable.

[Northernguy]

How big is your shark? It doesn't belong.Either does your regular pleco.They both get too big.
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Your schools are too small and your tank isn't big enough for that many schools.Your tank will also look too busy with that many different schools.
Get more corys.a school of no less than 6.
More tetras or any of the livebearers.
I think the shark may be responsible for the lost fish.If they fit in its mouth its a good possibility!