The best hope to get mangrove jacks is a fish farm, since its a food fish here and bred. commercial fishing ponds also stocks them with mangrove jacks because they are cheaper fish, they called it "chia cho" in dialect or common snapper, likewise for barra, or lates calcarifer, food fish and bred in huge numbers. The best way to get them is to ask the fish monger or the fishing pond owners although i seriously doubt that its been converted. Bumblebee grouper is rarer and expensive, saltwater barracuda, never seen it sold converted or not.