I got him at 10 inches and I had an 80g when I bought him but it began to leak so I had to put him in the biggest tank I had available until I could get the new tank. I did put in a powerhead and some extra decor and it is looking a little better.That doesn't make sense at 10 inches he should of been out of a 50 gallon years ago......I figured he would of gotten a chimple in the 50 from not having enough space....I'm guessing now that he has more room he is exploring ....you should of gave him a bigger tank 2 inches ago .....I would add a good amount of flow with powerheads and give it about 2 weeks..... don't make him finger chase or startle him ...give him some time to adjust to the space ....