My fish keep on dying

Question
Hi, I have gotten beta fish from Wal-Mart all of the time and they always died as soon as I got home, I finally decided to get a tank full of fish. Well, four of them to be exact. My tank is pretty good sized, plastic, and I had an Angel fish, a Shark of some kind, and 2 other agressive fish, I dont know what kind they are though. I have a pump in the tank, I feed them well, twice a day, I feed them the right kind of food. They have plenty of hiding spaces, artificial plants. I clean there tank out often; twice a month! What am I doing wrong because the shark and angel fish both died today. Can you please give me some information, or tell me what I am doing wrong?! Thanks.

Answer
Savanah,

When you got the fish in your bag, when you got home did you keep your fish in the bag and let them sit in you tank for about 15 minutes. If not then that is probably why, they need to get use to their new water. If not, then your water levels may be high and you can test them with kits and you can buy them at pet stores.

Thanks.
BethE.