in reply to orangecones...
I have a BS in Biology and an MS in marine biology from Stony Brook (NY). As for the fish outgrowing, I also have a 75 gallon which I transfer them into once they outgrow the smaller one. I usually start them in the small tank to serve a purpose until they "upgrade" to the larger one. I also keep the little tank for the smaller ones like the tetras, barbs, etc. Once I transfer them, I get a smaller replacement and put them in the 20 gallon. So right now in the 75 gallon I have 3 bala sharks, about 7-9" each, 2 kissing gouramis about 5-6" each, 3 clown loaches, about 6" each and 6 giant danios, about 3-4" each. All started in the small tank and moved up to the big one.