Yeah I know, I was trying to stress that puffers are not a good option. assassins can be fed on meaty sinking pellets too as they are carnivorous.
I kept congos, cichlids, cigar sharks and rainbows together last year in a 225 and Honestly I am unsure towards the rainbows. they have a very high prey
Then you end up with puffers that you have to buy snails for and assassins that you have to buy snails for, adding stock is never a solution.
The best snail eaters are puffers but they also like to munch on the fins of other fish. Your best bet would probably be manual removal. You could grab
Nathan your tank looks fabulous, kudos!