Well I understand if you don't have a choice but, your tank is so overstocked that keeping all of the fish probably isn't going to work out too well. Since you don't have a test kit, as mentioned in another thread, I'm guessing you haven't cycled this tank and have been adding all of these fish w/o testing your water, so you will likely have fish die off due to build up of toxins like ammonia and nitrite. The amount of waste all of your fish are producing is too much for a tank of this size. And keeping active catfish that reach 3" in a 7.7 tank is just cruel in my opinion. Your best bet would probably be to do daily water changes until you can test the water if you want to keep the fish alive. I would highly recommend in the future when stocking a tank that you do not make impulse purchases, and thoroughly research the requirements for each fish you want.