how big are the perch? i ask because most perch that i have encountered are about 6-9 inches. and if that is the case for yours, then the tank is overstocked.
im not trying to be rude, but ive never heard of anyone keeping perch in a tank.
you are going to need a filtration unit of some kind. biowheel filters are relatively cheap to buy. get one rated up to a 50 gallon tank.
here is a bit of info that i found for you...
After you have obtained your fishes, there are two major concerns when looking at keeping these types of animals. One is size, because many North American fish grow large quickly. The other consideration is temperature. Depending on where you obtained your fishes, (from the wild or a fishery), they may need a tank that stays cool. The best way to keep any aquarium environment cool is with a chiller. Many North American fish species prefer temperatures between 50 and 70 degrees Fahrenheit. In many cases temperatures that exceed 75 or 80 degrees Fahrenheit can harm or even kill these animals. I canâ€™t think of any instance where bluegill, bass, walleye or perch were kept in environments that reached high tropical temperatures for continuous periods of time.
The next issue that you will find with North American fishes is their consumption of food and production of waste. Because these fish are fast growing and many are powerful predators, they eat a lot. I would suspect that you will need to start these animals off using only live foods such as grass shrimp and feeder fish. You will need to condition them to accept prepared or frozen foods. Your goal in the end would be to have an aquarium full of fish that accept easy-to-feed prepared foods. You will likely find that these fishes grow very quickly, and in the case of large- or smallmouth bass consume anything they can get into their mouths.
That leads to the next thing to remember when looking at these animalâ€™s requirements. You will need a very large aquarium! I would recommend a 180- to 200-gallon tank when hoping to house large North American fish. I would also recommend a sand bottom and lots of rockwork for hiding. Natural or artificial plants could be employed and while it may not be native, anacharis makes a hardy addition to any captive freshwater environment.
North American native fish species are not really tough keepers but just fish that have a slightly different set of requirements than the tropicals we know and love. Cool water, a large aquarium, plenty of food and frequent partial water changes are all part of the equation that leads to successfully housing these unique fishes.