bala shark: many people on here have that size or larger tank (myself included for the most part). It's just because of how grossly overstocked that one is that makes it worth mentioning. you need to get rid of/ get a bigger tank for everything in that tank except the platies, and eventually even they will over populate the tank. balas grow to 12 " need tank about 125g also need to be kept in a school. goldies grow to 18" best to be kept in a pond also need different temps than other fish (coldwater, max. 72f). common pleco(assuming thats what it is) grows to 2 ft., needs min. 280g tank to live healthy for all of it's life. I know it's hard to bring fish that you've had for a long time back to the store, but they'l be much better off that way (unless you get bigger tanks). also if your dad won't get you a bigger tank,find some work for the summer and put all (or most) of the money into a bigger tank(s). It's what I'me doing