The cherry barb (Puntius titteya) is popular within the freshwater ornamental trade for its bright red coloration and schooling behavior within community tanks. The species is widely available from overseas producers but is also currently in aquaculture production in the United States. There has been little research on the life history or culture techniques for this species, and such research is needed to address bottlenecks in larval rearing to improve production efficiency in the United States. Larval fish encounter several ‘critical’ periods during development which can lead to mass mortality events that involve the loss of significant quantities of larvae. Larval mortality is often attributed to poor nutrition during development. Identifying appropriate nutritional protocols is vitally important for the survival and growth of larvae. Chemosensory and visual cues are important for successful prey capture by larvae. Larval feeding response can be impacted by additional factors, but low feeding incidence in the presence of abundant prey items may be indicative of poor prey visualization. Gaining a better understanding of visual system ontogeny in larval fish can help predict appropriate lighting and environmental protocols required to increase feed ingestion rates.
For this study, retinal ontogeny of P. titteya will be described using microspectrophotometry. Microspectrophotometry (MSP) can determine the spectral absorption properties of photoreceptor cells and then be used to characterize the development of the visual capabilities of fish larvae throughout early life history. P. titteya larvae will be dark adapted before undergoing dissection for retinal isolation. The retina will be macerated on a cover slip to target individual photoreceptors with the MSP. Measurements obtained will illustrate a maximum absorbance curve for a singular photoreceptor (Figure 1). The collected data can help inform culture conditions such as wavelength and light intensity that would be most conducive for effective prey identification, capture, and ingestion by larval fish. Manipulations in lighting conditions during the larval stage may help to promote larval feeding incidence, growth, and survival, and ultimately increase production efficiency of P. titteya.