For food I would just try a different food. Mine will eat anything that is put in the tank usually.
I know what you are going though with the shark though because I have had the same set up as you(tigers and rainbow) for about 3 years in various sized tanks, but now in a 65. I don't really see tiger barbs as aggressive although it is always said that they are. The tigers will never get back at the shark no matter the tank size. The will however have more room to get away in the larger tank. In such a small tank the barbs will always be in the sharks territory and will always be an enemy. In a larger tank that may change, but it also may not.
Good luck with you set up. Rainbow sharks have really beautiful colors when colored up and there size at full grown is really a site to see as they move about the tank. The semi-aggressive nature and sometimes out right hostile one at times is what I view as their only negative.
RM
I know what you are going though with the shark though because I have had the same set up as you(tigers and rainbow) for about 3 years in various sized tanks, but now in a 65. I don't really see tiger barbs as aggressive although it is always said that they are. The tigers will never get back at the shark no matter the tank size. The will however have more room to get away in the larger tank. In such a small tank the barbs will always be in the sharks territory and will always be an enemy. In a larger tank that may change, but it also may not.
Good luck with you set up. Rainbow sharks have really beautiful colors when colored up and there size at full grown is really a site to see as they move about the tank. The semi-aggressive nature and sometimes out right hostile one at times is what I view as their only negative.
RM
