# Nutritional and Microbial Responses of Pocillopora verrucosa to Co‐Culture With Chromis viridis Damselfish

## TL;DR

Culturing corals with damselfish and live feeds improves their nutrition and restores a natural microbial community.

## Contribution

Fish co-culture and live feeds enhance coral microbiome similarity to wild corals and improve nutritional status.

## Key findings

- Co-culturing corals with damselfish and live feeds increases protein and lipid content.
- Captive corals showed reduced storage lipids compared to wild corals.
- Endozoicomonas-affiliated bacteria were only maintained in corals co-cultured with fish and live feeds.

## Abstract

Associations with fish can benefit corals by increasing growth and stress tolerance. To investigate microbial and nutritional responses of corals to fish associations in the context of enhancing coral aquaculture outcomes,
Pocillopora verrucosa
were cultured for 3 months with different combinations of live feeds and schools of juvenile
Chromis viridis
damselfish. The combined live feeds and fish treatment resulted in a bacterial community most similar to wild
P. verrucosa, dominated by Endozoicomonas‐affiliated taxa. Protein content was enhanced in corals with access to live feeds and/or dissolved fish wastes compared to unfed controls. Total lipid concentrations were elevated in captive corals with access to dissolved fish wastes and at moderate levels in those supplied live feeds, likely due to the activity of corals' symbionts and deposition of derived lipids from live feeds, respectively. However, all captive corals demonstrated a significant reduction in storage lipid concentration compared to samples from the wild. Fatty acid analysis indicated these shifts were likely the result of higher light levels in the field supporting Symbiodiniaceae photosynthesis and potentially feeding on wild zooplankton. Co‐culturing captive corals with fish and providing appropriate live feeds may therefore offer an effective approach to improve coral nutrition, health and microbiome stability.

Assessing the microbiome of captive
Pocillopora verrucosa
corals showed that populations of proposed microbial symbiont Endozoicomonas could only be maintained when corals were co‐cultured with
Chromis viridis
damselfish and supplied live feeds. Therefore, utilising fish co‐culture in coral aquaculture may be useful to support coral microbial populations.