Too many fish, too small tank, aggressive fin nippers; no problem! 8 Gallons, 21 fish: 8 Tiger Barbs, 3 Sumatra Barbs (Green). The Greens are also Tiger species so school together. 2 Zebra Loaches, 2 female Swordtails (will get males), 6 Cardinal Neons. I grew up with a small 5 gal community tank and I want my six year old son to experience what I did, to learn a little about life. But, I'm in the Philippines now and the LFS don't carry many species. The Tigers were my first purchase because they were small and interestly active, and the 2 loaches. I knew nothing about tiger barbs. I got 5. Shortly thereafter I got three guppies, 2 males and a female, all another store had. They seemed ok. I noticed the barbs were flashing, rubbing on the shells and knew ich was a possibility. I put in medicine, raised temperature, and stopped feeding as recommended. The last was a bad idea. When hungry the tigers ate the tailfins of the fantail guppies, and they died. Then the female disappeared. I think she jumped out of the tank. I want guppies because the make lots of babies, and K want my son to see nature in action as I did. The medicine killed my plants. I read that a minimum of tigers around ten fish will keep them busy deciding who's boss among themselves. I got six more and let them settle in, and two female swordtails, and one pink Danio, a glowfish, all they had. They are fast or quick enough to dscape nipping barbs and there is no problem. The barbs leave them alone starting one day after introduction to the tank. I found a store in Cebu City. They had six Cardinal Neons. I love these peaceful beauties. I got them all. But many predicted they wouldn't last a day! What to do? They needed to adjust to tank temperature so I put the plastic bag in the tank. The tigers began going to the Neons immediately and bumped the plastic bag trying to get to them. The Neons didn't seem afraid, curious about the barbs, safely in the bag. I left them safe in the large bag for four hours. I wanted the tigers to get bored and stop being interested in them. That happened in about three hours. Then I fed the Barbs! A little later, I put the Neons in the tank, and watched, and waited! The Tiger Barbs left them alone as they had for the last hour, 4 total. It is now a week later with no problems! Yea! I change 25% of the water once a week or more. I clean the small sponge filter once every two weeks or sooner. There is also a stone bubbler next to the filter. I will get new plants, both rooted and floating, for hiding places and oxygen, then try to add guppies again, following the same procedure. I believe the Tiger Barbs vie for leader of the pack and keep busy among themselves, but I feed three times per day for insurance. They are wolves! So far, it's a Tiger Barb dominated, peaceful community tank. The Swords and Neons and lone Danio, (until I can get more), swim among them and/or school together with no hassles. The Neons hang out in the calm water away from the bubbler current. The Swordtails love the bubbles & current. The loaches are bottom dwellers but also very fast. The plants are essential, and I have many sea shells that offer hiding as well. We'll see. I know, I will eventually get a much bigger tank! It's a matter of space for the present time. I will keepnyou posted. So far, the Tiger Barbs, well fed and all 11, are pussycats!