Coral fish experience a very strong predation pres� sure during all their life cycle. This factor is considered to be the major evolutionary and ecological determi� nant in the ecosystem of the coral reef. Recently, mutualism and parasitism increasingly attract atten� tion. The mutualistic relationships of fishes and coral are well known. The coral colonies are reliable shelters for fish, fishes clean the corals from slime, sediments, and parasites, fertilize them, and ventilate the space inside the colony [1, 2]. Being in such a close symbi� otic association with the colony of a host coral and various symbionts, fishes are exposed to infestation with parasites, and the damage may surpass the advan� tages of mutualism. Mutualistc associations of fish with corals differ in the character of topic, trophic, and social relation� ships, as well as the duration of the existence of fish in the colony. Two types of symbiotic relationships are distinguished [3]. Inbiont fish, after the larvae settle from plankton, stay for all their remaining life within the host colony, feed on coral slime and on symbiotic invertebrates. As a rule, they are territorial and never leave the colony. Their abundance in the colony is low. Parabiont fish are closely connected with the coral during much shorter period of their life, namely, in the period of rapid growth. In the period of reproduction, they break symbiotic association and form reproduc� tive groups. Stable groups of parabionts usually consist of a few dozen fish. In the light part of the day, they stay near the host colony and feed on plankton brought by water currents. In the dark part of the day and when frightened, the fish hide inside the colony. Differences in ecology and behavior of inbionts and parabionts are unavoidably reflected in the appearance of communities of parasites in coral fish. It may be expected that inbionts, which are in close con� tact with each other and with other members of the symbiotic association within a limited space of the host coral, are exposed to higher risk of infestation with various parasites. On the other hand, the para� bionts feeding on zooplankton and symbiotic inverte� brates may get more parasites via trophic interconnec� tions. Negative influence of a high infestation with parasites may deteriorate the advantages of the symbi� otic life [4, 5]. Which type of symbiotic relationships of corallobiontic fishes has a higher risk of infestation? To answer this question, we investigated the com� munities of macroparasites of inbiont and parabiont fishes living on the mass species of scleractinian corals Pocillopora and Acropora from the coastal waters of South Vietnam (Nha Trang Bay). The material was collected in April–May 2012–2014 using light diving equipment at depths from 3 to 8 m. Separately situated colonies of corals were covered and wrapped in a piece of plankton gauze (all parabiont fishes which hid among branches of the colony were collected as a gen� eral sample, together with inbionts). Then, they were separated from substrata and placed into vessels with sea water. The fish from each colony were kept in sep� arate aerated aquaria.