All my fish are dying, can anyone help?

Hello,

I've had my tank (10 gallons) for about 3-4 months now. All the fish were doing fine up until 3 weeks ago when my tiger barbs started dying.

Ammonia, Nitrate, and Nitrite levels are all 0.
Ph and water temperature are fine.
I have tried a broad spectrum medicine, parasite tablets, and bacteria medication.
Every week I do a 10-15% water change and every 5 weeks I do a 20% water change and vacuum the gravel.

So far I have lost 7 tiger barbs and 1 algae eater. Currently in the tank I have 3 mollies and an algae eater.

The dead fish have no visible spots or scale discoloration. But, whenever they seem to be near death they stop eating, stay away from the other fish, and swim near the top of the tank at odd angles.

Does anyone know what may be wrong with my tank? All suggestions are greatly appreciated!

Thanks so much!

[marissposa]

I am sorry to hear of your losses.  Are you using a dechlorinating water conditioner?

[PrettyKitty1]

Where are you getting your fish from?

What are you feeding your fish?

Are you putting salt in the water?

That I know of, the ideal water condition for mollies is salt added to it. Although tiger barbs don't require this, they can stress each other when there are less then 12 in the tank.

A 10 gal tank is too small for a relatively big population of fish. Have you tried reducing the amount of fish you have see how that goes? I have 8 female fighting fish in a 20 gal tank and so far so good.

Your fish may just be stressed. Stressed fish stop eating. It could be there are too many different fish living in that tank or it could be you're buying unhealthy fish.

Have you resarched on compatibility?