Effects of abnormal lighting on the development of zebrafish visual behavior

Studies across several species have demonstrated that the developing visual system is influenced by environmental conditions. This study examined the effects of abnormal lighting environments on zebrafish visual behavior. Zeb rafish were raised under different lighting conditions from fertilization t o 6 days postfertilization (dpf). These conditions included a normal light/ dark cycle, constant dark, constant light, as well as exposure to Various l ighting cycles with intense light. Visual acuity was tested using the optom otor response to black and white vertical stripes of various widths. The re sults showed that visual acuity of the normal fish improved with age. In ad dition, fish raised in constant light had significantly lower visual acuity than fish raised under normal lighting conditions. Subjects raised in cons tant dark showed somewhat lower visual acuity than normal subjects when tes ted at 12-14 dpf, but the deficits were not as severe as those found in fis h raised in constant light. Intense light rearing did not have any substant ial effects on visual development, unless it was constant. In conclusion, u nder normal conditions, zebrafish visual acuity improves with age, supporti ng previous work on zebrafish development. In addition, zebrafish visual be havior is altered by abnormal lighting conditions; the most severe decremen ts occur when raised under constant light. (C) 2000 Elsevier Science B.V. A ll rights reserved.