Help!?

[Ana]

Hi,
I am new to the keeping of fish... I have 2 corrys, 5 cherry barbs and a common plec and a dead silver shark
My silver shark, Bruce, was my first fish, I got him june 06 as a small 2 inch fish, then in july I got 5 cherry barbs and in october the two corrys, Will and Lyra, and the plec, Lemmi.
The corrys developed white spots in the first week so I treated them for whitespot with King British white spot control, the spots desappeared and they were all fine. The corrys proceeded to lay eggs everywhere in the tank and whilst this was happening the male corry started bullying Bruce by chasing him all around the tank, but it didn't last and it wasn't regular.
Around Christmas I noticed Bruce had a few scales missing, but these soon grew back, I read that live/frozen food was better for them so I fed them frozen food rather than granules and Bruce was feeding really well, absolutely loved the frozen food and wasn't showing any signs of illness... Then end of last week i noticed he had a couple of scales missing again but apart from that there was no other signs of illness then he just died on wednesday....
I immediately did a water change and treated the tank with interpet methylene blue as a prevention, I have now noticed my cherrys and my corry cats rubbing themselves on the plants and the gravel a few times, there are no other visible symptoms and they are behaving and feeding normally but as Bruce died I am really worried for the rest of my other fish. ANY IDEAS WHAT IS GOING ON? Please help?!

 

[WILDER]

Need to look at tank size in gallons or litres.
Water stats in ammonia,nitrite,nitrate,and ph.
As bad water quality can make them flick and rub, so need to rule it out.
The shark needed a 90 gallon tank and also need to be kept in a shoal, no less than 3 of them.
They will die of stress on there own.

 

[andywg]

I have never heard of a silver shark dying of stress from being on its own. They will become very skittish when kept in lower numbers and more is definately better.

Lack of scales sounds like any silver shark. They are prone to scaring themselves and flying across the tank. At least one of my 7 will be carrying a knock of some sort at all times. I would say there is a possibility that the fish has injured itself, especially if not in a long tank. I have had 4" silver sharks "knocked out" (only breathing, no movement and unable to control buoyancy but no signs of stress or struggle) for up to 10 minutes in a 6 foot long tank where they have beomce skittish and started flying around and trying to get out.