Pearls are a lot more peaceful than other gouramis. They'll do well in a 33g as long as there's plenty of plants. They won't bother any other fish you have in there. You might see some chasing going on every now and then, but it's nothing. I have one in my 55g tank right now and he got along great with my blue gourami until my blue gourami starting chasing my juvi severums..I got rid of the blue gourami.