Trouble with pencilfish

[Maramcd]

I have been having trouble keeping my pencilfish healthy and alive.  I started with ten. I lost two last month with no clear signs of illness other than being a little more shy. I lost one last week from dropsy (caught too late), and I just found another one that looks like it has dropsy. I just put it in a 10 gallon isolation tank with aquarium salt. I am trying to figure out what's causing this.

 

I have had my current tank fully set up since February. It's a 37 gallon, and it has 2 ram cichlids, 7 amano shrimp, 7 cherry barbs, 5 kuhli loaches, and 7 red arc pencilfish. The rams were bullies at first, and then they figured out what section of the tank they wanted to be their territory, and have been fine since then (a bit nippy with the barbs during feeding time, but otherwise fine). I feed crushed tropical fish flakes, cichlid pellets, and sometimes bottom feeder tablets. I feed frozen food 3x per week: daphnia, brine shrimp/spirulina, and bloodworms. I feed a small amount of crushed flakes when I feed frozen food that is too big for the pencilfish' tiny mouths. Lights are on for 2 hours in the morning and then another 7 hours in the afternoon/evening. Algae is mostly under control (I found a small amount of blue green algae that I am prepared to treat but am tackling other problems first).

 

pH: 7.2

ammonia: 0

Nitrites: 0

Nitrates: 20-40, usually 20-30

GH: 8

KH: 3

Temperature: 81-82

 

Any ideas?

[TheSwissAquarist]

Could be internal parasites? 
 @Colu

[Colu]

Bloating can be caused by internal parasites organ failure typically you will get the odd random deaths weeks apart with parasitic infection what I would suggest is treating with paracleanse once every two weeks for 3 full courses of treatment if you still losing fish after the Frist course of treatment give us an update @Maramcd