I have been keeping trout for 4 months now. I have one rainbow which is 5 inches long, and two browns which are about 4 inches. They live in a 30 gallon tank with two bubble walls and a small current. I have no cooler and my fish seem to be fine. I keep the window open at night so the temperature cools down and stays somewhat cooler during the day. I change the water 10% every week, adding de-chlor, and ick treatment so the fish dont get sick due to any temperature problems. The trout live with a small plecostamus, and dont seem to bother him. The rainbow is much more aggresive than the browns and eats two large meal worms a day. I cut the worms in half and feed him a half at a time. one worm in the moring and one worm at night. The browns eat small pieces of cheese. I give my rainbow an occasional housefly or grub from my yard. He eats spiders and "roley poleys". The browns arent very aggresive as though they try to jump out of my tank in the evenings. i belive this may be instinctive. I keep the water a little low so i can watch the fish leave and come back into the water during the evenings. The rainbow is a very beautiful fish with a very aggresive personality. he sees everything which goes into the tank and is very territorial. i have several peices of driftwood and four plastic plants. i collected lava rocks and some flagstone which makes nice caves. my tank has a very high amount of oxygen in the water. i caught these trout in my creek next to my house and hope to see them live for many more years.