[garfieldnfish]

Tiger barbs are 2.75 " a piece. They are low waste fish and a 20 gal would normally be big enough for a school of 7 fish with their waste factor. But tiger barbs are very active and aggressive fish. If kept in large enough groups this stays amongst themselves. I really don't believe it makes a difference if the are green, regular or albino. They are just establishing their pecking order. Plants might help, some decoration a chased tiger can duck into will improve the quality of life for the more timid ones. But in all reality, tigers are better off in a 30+ tank. And remove the goldfish, please. That is not a tank mate for tigers. Beside the fact that a goldfish need 15 gal for himself because of his large poop factor, a common or comet needs more swimming room and a fancy will sooner or later attact the attention of the tiger and you can expect some shredded fins.