Alright, so I have 0 full grown fish. I have 4 half grown fish. I do water changes as least once per week, instead of most people who do it once every 2 weeks or more. There are no live plants in the 10 gallon as I tried it for a couple of days once but the fish kept de-rooting it. In the 23 gallon, the filtration is so over-kill that I only did a siphoning after 2.5 months and the water I siphoned out into a bucket was crystal clear and had no dirt in it! It's also an undergravel filter with an over kill power head *shakes fist at sales person!* and I would estimate you could probably keep about 50" of fish (1-2 inch per fish) in there if you did water changes once a week! In my 30 gallon, I have 10 fish (1.5-2" in size) and they take up about 1/8th of the tank and I have a fluval 203, and live plants in that tank. I've done two water changes in that tank in the month that I have had it, but it really was not necessary. Anyway, home time now! bye!