I have a twenty gallon tank with three female long-finned rosy barbs, one regular male rosy barb, and three male odessa barbs, plus two pepper cories. The poor AquaClear 20 that is trying to keep up with this crowd is not managing well. The tank is three years old and I have some other issues with it (I added salt for the first year, and the KH is through the roof; 40% weekly water changes for the last year haven't changed it at all). The space I have it in can handle a 29 gallon, but will that be big enough? I have read that these barbs can get up to 5" long, but I have never seen any even close to that. I bought the odessas four months ago, at about 2" long. The rosies I have had for a long time, and they have grown to about the same size, and very stout. How big might they really get?