Hi everyone! I could really use some advice concerning my tank below and upgrading to a larger, hopefully happier tank.
Background: I have had my tank and cichlids for about 3 years now. My tank is a 40 gallon (breeder style?) it is short and wide. I have made upgrades in this time, mostly trying to decrease their aggression through giving them: ceramic rocks with holes in them, sand instead of pebbles, lake salt added during water changes...
It seems though they have gotten more aggressive! Especially the king of the tank in the picture below who changed from blue and acquired a yellow color and then got really mean! I hold him mainly responsible for killing 2 of my other cichlids and a good size catfish.
I recently acquired a 55 gallon which I plan to move my remaining 4 cichlids to. I am not concerned about the move and have done a lot of research on how to minimize their stress during this process.
I don't want the same old aggressive tank where I never see my fish and they try to kill each other every time someone moves. What do you think? Should I remove the rocks with holes to hide and replace with a normal rock structure? I recently found out about heavy stocking of a tank to decrease aggression. I would love to increase the number but is it necessary to get multiples of the same species? Any advice is greatly appreciated. This tank is a hostile environment!

Background: I have had my tank and cichlids for about 3 years now. My tank is a 40 gallon (breeder style?) it is short and wide. I have made upgrades in this time, mostly trying to decrease their aggression through giving them: ceramic rocks with holes in them, sand instead of pebbles, lake salt added during water changes...
It seems though they have gotten more aggressive! Especially the king of the tank in the picture below who changed from blue and acquired a yellow color and then got really mean! I hold him mainly responsible for killing 2 of my other cichlids and a good size catfish.

I recently acquired a 55 gallon which I plan to move my remaining 4 cichlids to. I am not concerned about the move and have done a lot of research on how to minimize their stress during this process.
I don't want the same old aggressive tank where I never see my fish and they try to kill each other every time someone moves. What do you think? Should I remove the rocks with holes to hide and replace with a normal rock structure? I recently found out about heavy stocking of a tank to decrease aggression. I would love to increase the number but is it necessary to get multiples of the same species? Any advice is greatly appreciated. This tank is a hostile environment!


