Wild populations of the green mojarra Cichlasoma beani, are being pressured by anthropogenic activities. It is possible to mitigate the deterioration of native species populations by developing culture techniques. Environmental factors such as light intensity and photoperiod may affect the development of fish under culture conditions. Therefore, the aim of the present study was to examine the effect of these factors on growth, survival, and condition of C. beani cultured in different light intensities and photoperiods. Light intensities of 1000, 1500 and 2000 lux and photoperiod 24:00, 16:08 and 08:16 Light:Dark (L:D) were tested in 40 L tanks (10 fish per tank, three replicates per treatment) during eight weeks. There were no significant differences in light intensity or photoperiod, which was associated with the natural adaptation of the species to these factors. The results also suggested the favorable overall growing conditions during the trial and he response of the life cycle stage of the specimens used in this study. The results of the present study indicate that the natural adaptations of C. beani, allow the favorable culture in various light conditions in juveniles, which can be advantageous for commercial culture as may imply low energy costs.

Yellowfin tuna has a high level of free histidine in their muscle, which can lead to histamine formation by microorganisms if temperature abuse occurs during handling and further processing. The objective of this study was to measure levels of histamine in damaged and undamaged thawed muscle to determine the effect of physical damage on the microbial count and histamine formation during the initial steps of canning processing and to isolate and identify the main histamine-forming microorganisms present in the flesh of yellowfin tuna. Total mesophilic and psicrophilic microorganisms were determined using the standard plate method. The presence of histamine-forming microorganisms was determined in a modified Niven's agar. Strains were further identified using the API 20E kit for enterobacteriaceae and Gram-negative bacilli. Physically damaged tuna did not show higher microbiological contamination than that of undamaged muscle tuna. The most active histamine-forming microorganism present in tuna flesh was Morganella morganii. Other decarboxylating microorganisms present were Enterobacter agglomerans and Enterobacter cloacae. Physical damage of tune during catching and handling did not increase the level of histamine or the amount of microorganisms present in tuna meat during frozen transportation, but they showed a higher risk of histamine-forming microorganism growth during processing.