redtail shark is dying

Question
hi,my redtail shark is not looking or swimming too good,i have him in a 180ltr community tank with neons,gouramis,plecos,bettas(1 male and 2 females)clown loach,congo tetras and rams.i first noticed he was shooting around the tank really fast and looking really grey.after a couple of days he looked like his buoyancy was bad and he was turning around as he swam.we noticed that his tail had a piece missing and treated the tank for fin rot but he just got worse and then our female bettas were teaming up on him and attacking him. we have segregated him to a bowl in the tank so he isnt stressed.could he have some sort of defect or illness.this is the first fish to die on us,and we're realitively new to this...please help
regards
Mark

Answer
Hi Mark,
Red Tail sharks get aggressive towards other fish when older.  They grow to almost 6 inches, and can terrorize a tank in no time flat.  You certainly don't have the fish to go with a Red Tail Shark.  When keeping Red Tail Sharks, you mush have many hiding places.  The fact that it is grayish in colour is a lack of hiding places in your tank, and living in a tank which is not comfortable for him.  The bettas are most likely afraid of him, thus stressed too, but will defend themselves if need be.  For a healthy stress free tank, you will have to bring him back to the pet store, and ask for a credit.  There is no possible way you can keep this fish with the fish you now have.
Check your water to see if you have ammonia, or nitrates in it, and if you do, make water changes until you are rid of it.  Ammonia is the number one killer of fish.  You can buy this small kits at your pet store, and they should be number one in your fish cabinet.
When buying fish, always read up on them first.  Not all fish are compatible, not all fish live in the same water conditions.  There are many fish families.  It is always best to read up on them, or ask, before buying a fish.
Hope this helps
Lynda