Black Ocellaris Clownfish.

Amphiprion ocellaris is one of the most docile clownfish species and poses no meaningful threat to firefish. Aggression in this species is entirely intraspecific (firefish vs. firefish); toward dissimilar tankmates like clownfish, firefish are passive and will simply retreat rather than escalate. The two occupy different water-column niches — clownfish near host anemone or rockwork, firefish hovering mid-column near the substrate entrance of their burrow — so territorial overlap is minimal.

Royal Grammas are territorial around a single chosen cave, and that defense is directed at fish with similar purple-yellow coloration or those that physically intrude on the cave. Clownfish share neither trait. Compatible with clownfish; both species ignore each other in practice. Adequate rockwork (30+ gal tank) eliminates even theoretical stress.

A slow-moving, mid-water fish with no meaningful aggression toward dissimilar species. Clownfish and Banggai cardinals peacefully coexist. The only documented aggression concern is male-vs-male intraspecific rivalry, which does not involve clownfish. Both species are reef-safe with identical salinity and temperature parameters.

Interspecies behavior toward clownfish is reliably peaceful — chromis school in open water and ignore benthic or anemone-associated fish entirely. All documented aggression is intraspecific (dominance hierarchies within the school) and does not involve clownfish. Reef-safe, no fin-nipping toward clownfish, and water-parameter requirements overlap exactly with A. ocellaris.

Tiny, docile fish that perches on coral branches well apart from clownfish territory near anemones or rockwork. The genus is broadly peaceful toward other fish species — intraspecific aggression (goby vs. goby) is the only real concern. The citron goby (G. citrinus) is more assertive; the yellow and green Gobiodon species commonly sold are non-aggressive community fish that are compatible with clownfish.