My son has a 10 gallon tank which is my old tank. I have recently upgraded to a 40 gallon tank. Problem I am having is recently it seems the tank has become a death trap. He orginally had two danios, a guppy, a betta and a chinese algea eater in a smaller tank. Well my daughter has the smaller tank now and I put the chinese algea eater in it. It doing fine. Now I decided to put a plecuasnamis not sure on spelling in his tank. Well I got one from Petsmart, it died in two days got another one it died in a week? We also added a little ornament to his tank which the paint started to chip. So we took it out got a pleco algea eater from Petco and it has lived for about two weeks when I found it injuried this morning. This past weekend we added a blue tail guppy and a small volcano for bubbles. Well the guppy died in two days. Which was Monday. His three month old Betta I found dead in the volcano. And now the pleco I found injured and almost dead. The pleco liked to go in the volcano like the Betta so think he got injured in it somehow. Ok Now the two danios and one guppy are doing fine. The water test showed great except the PH was high possible alkaline. Only thing I can think of is the betta and pleco go trapped in the volcano? The new guppy I have no clue? Sorry seems kinda long but I don't like loosing fish and don't want to loose anymore just looking for thoughts. I have a 40 gallon tank and my daughter has a 5 gallon tank both are a couple months old and had no issues