I have a cover on the filter.. I have a 20 gallon long tank.. And I HAD 7 fish in it.. Now only 4.. And the filter has sucked A LOT of them up.. So.. I need help and quick.. I have seperated two of the goldfish.. One of my tropical fish are sick.. And I had another tropical in the tank.. The pale pink tropical fish color always stays to the bottom of the tank but its still alive.. The grayish blue fish rocks back and forth and rams into walls several times.. The two goldfish [calico color] were swimming just fine.. So I seperated them.. Now I have the calico ones in a round fish bowl with a little colder than luke warm water in it.. I have a light on top of it too.. Thanks for the help :]]