As anemonefishes of the genus Amphiprion are emerging as a model organism for marine science, it is critical to have standardization in housing and husbandry protocols for research laboratories. Here, we conducted a literature review, a questionnaire survey, and two experiments regarding the housing and husbandry of anemonefishes for use in research. The literature review identified the need for standardization and optimization of multiple variables including tank volume, diet composition, and lighting type for the housing of broodstock pairs. The questionnaire survey was completed by 27 laboratories, with a 45% response rate, across 11 different countries in Europe, North America, Asia, and Australia. Results from the survey confirmed the need for standardization or optimization of laboratory protocols. The experimental manipulation of housing of Amphiprion percula was conducted over a 3-month period, where reproduction was monitored for 8 breeding pairs housed in large, 120-liter (30-gallon) tanks versus 7 breeding pairs housed in small, 9-liter (2-gallon) tanks. Results suggest that reproductive output was significantly reduced among breeding pairs in experimental 9-liter tanks when compared to those housed in standard 120-liter tanks. The experimental manipulation of husbandry of A. percula was conducted over a 3-month period, where reproduction was monitored across 19 breeding pairs on a high ration diet (1 mL scoop of pellets) versus 15 breeding pairs on a low ration diet (0.5 mL scoop of pellets). Results suggest that reproductive output was significantly reduced among breeding pairs on a low ration diet when compared to those on a high ration diet. Although the experimental 9-liter tanks were likely below the optimum for reproductive output, the fact that reproduction still occurred suggests that the fish will reproduce in tanks smaller than 120 liters and that 20-75 liter tanks may be the best option for housing large numbers of A. percula and similar species. The reproductive output of broodstock pairs fed a high ration diet is similar to that seen in the wild, and provision of higher quality foods (e.g., cuttlefish, shrimp, fish eggs, etc.) beyond commercial pellets may enhance survival of larvae. In conclusion, our research suggests that the anemonefish research community should be discussing the optimization and standardization of housing and husbandry or, minimally, recognize that housing and husbandry influence a wide range of traits and will influence the results and conclusions drawn from experiments.

A fundamental question of evolutionary ecology is, what determines body size? In general, the body size of vertebrates is thought to be relatively inflexible, a product of their genes, food, environment, and stress. However, vertebrate growth can be plastic in response to population interactions such as predator-prey and competition. While these relationships can elicit plasticity of vertebrate growth, mutualistic relationships have yet to be investigated. An iconic example of mutualism involving a vertebrate is the relationship between anemone and anemonefish. In this interaction anemonefish size is often positively correlated with anemone size. Here, I test the hypothesis that anemonefish growth is a plastic response to variation in anemone size. Juvenile clownfish (Amphiprion percula) of relatively uniform size were paired with sea anemones (Entacmaea quadricolor) of variable size and monitored over three months. The average anemone size over the course of the month was then used to predict the fish growth each month. Mixed model analyses verified that anemone area is significantly associated with both change in fish standard length and change in fish body depth. Fish in larger anemones grew more than did fish in small anemones. Remarkably, individuals in large anemones achieved this despite receiving the same amount of food as individuals in small anemones. This clownfish growth plasticity in response to anemone size might be adaptive if anemone area is a good indicator of resource availability in the wild, because it would enable the fish to maximize their reproduction without compromising survival. This study extends the understanding of how plasticity of vertebrate species can be influenced by a wide variety of population interactions.

The relationship between clownfish and sea anemones is a beloved and iconic example of marine symbiosis. However, ecological information in the eastern Red Sea about the endemic Red Sea clownfish, Amphiprion bicinctus, and its host sea anemones remains relatively incomplete. For example, previous studies report that A. bicinctus forms mutualistic relationships with three to five host anemone species in the Red Sea. But the reported number and combination of host anemone species varies substantially among sources and little is known about host anemone distributions at different scales on the eastern coastline. To better understand the ecology of A. bicinctus and its host sea anemones, we conducted 70 surveys in three regions of Saudi Arabia and one region in Djibouti. We then analyzed distribution patterns for all anemone species observed in these regions, to attain deeper knowledge of anemone habitat usage and relative abundance. We recorded six host sea anemone species associated with A. bicinctus in the Red Sea, one of which represents a new case of symbiosis, and we identified differences in species composition and abundance across different reef scales. We noted patterns of decreasing anemone diversity with increasing latitude, beginning at 20° N, and greater overall anemone abundance in the central Red Sea. We also used field and laboratory observations to examine anemonefish abundance, survival, and fecundity on different species of anemones at different life history stages. In sum, this thesis collectively identifies eastern Red Sea anemone hosts for A. bicinctus, evaluates their regional and fine-scale distributions, and assesses how different anemone species impact their anemonefish occupants on different levels.