I have had my tank up for about nine month. I started with five tigers (I know everyone will probably say it is not enough but that is what I was told was the minimum when I first was looking), two regular and three green. I also got three cherry barbs, a rainbow shark and a bristlenose pleco. I lost a few tigers and some other fish over time, as far as I know it was due to water quality, but I replaced them and things were fine for a time. I had never seen the tigers being aggressive towards any of the others, the rainbow was the main one chasing everything around. I know the cherries maybe should not be with the tigers but I have not seen them have a problem with the tigers. After losing two tigers a while back I waited a few months to buy more.

Once I knew the tank was stable (after changing to a soil substrate) I purchased two more tigers, one regular and one green, both being at least half the size of the older ones. I noticed the new regular tiger hanging out around one of the older ones a lot and thought it was kind of odd but never thought about it further. About two weeks later I noticed a cherry had died, I did not look at it to see if there was any damage to it, but now I wish I would have. I took a second look at what the new tiger was doing around the older ones and it was nipping at their lower fins, some of them have damage to their fins, but the older ones just swam away, they don't chase him off even though they are bigger. I have not seen the new tiger chasing the cherries but I suspect it may have caused the death of the one cherry, water parameters were good when he died (0 ppm ammonia and nitrites and 5-10 ppm nitrates). Up until now the tiger cherry mix has not been a problem, there was three tigers and three cherries for many months, nor has the number of tigers been a problem, as far as I could tell.

Is this new tiger just overly aggressive, especially towards the other tigers or are my other tigers just not very aggressive? I was thinking about trying to go back to the store and see if they can swap it out. Is there anything else that I can do to put him in his place since the other tigers wont?