require some help

Question
i have purchased a new 75 gallons aquarium i want to make it a community aquarium
especially including ballon mollies,ponds fish,medium sized goldfish and blackmoors >can that be possible?
how many balloon mollies can be kept in
75 gallons aquarium
one thing else while changing 5% or 25% water every week the new water should be conditioned with anti cholorine and methylene blue or it will be pored straight away into aquarium water

i had one black moor which died and its body was having thing like white powder and its fin were rotten
can u tell why it happened ?and what was that?

And can fish kepping be economically benificial?

Answer
hello Wajid:  I would not keep molly's with pond fish. Pond fish such as koi and goldfish are cold water fish and Molly are tropical and need to have warm water.  You can house one inch per gallon of water for tropical fish... so up to 75 inches of fish at their adult size... or you can house  7-8 pond fish or goldfish... they need ten gallons of water per goldfish/pondfish.  Pondfish and goldfish produce a lot of ammonia so do not over stock your tank.  When changing the water use a water condition BUT DO NOT USE methylene blue or any other medication as it will kill off your beneficial bacterial colonies and then you will have water chemistry issues which will lead to fish loss.  It sounds as though the black moor that you lost had a parasite infection... or a chemical burn which would have been caused by high water chemistry levels in your tank.  Fish keeping can be economically beneficial... For example I have 22 fish tanks at home and my fish produces babies/fry that I sell to support my hobbies. I also grow aquatic plants and when they produce new plants or out grow tanks I sell those too.  dave