When my IT was small (around 2"-3") dither fish made a huge difference. He had been in a 30 decorated with rock caves and a lot of plastic plants but he constantly hid and was always unstable. I moved him into a 100 with the same style of rock caves and plants, and a dozen rainbowfish. The next day he was out in the open and bright as can be. He never looked back and remained stable for as long as I had him (until he was about 7").