Zebrafish

Studies also tested effects of social stimulus such as presence of conspecific because zebrafish are known to social fish, they school and shoal (Bisazza et al., 2000). Two studies tested this effect they found similar results regardless of sex of fish. In first study, the researchers presented a testing fish with a group of unfamiliar fish and they found left eye to be dominant when observing the group (Sovrano and Andrew, 2006). Another study that also tested for sex differences besides the effects of conspecific, found similar results left was dominant (Ariyomo & Watt, 2013). There were no visible differences in males and females, left eye was dominant in all the conditions (Ariyomo & Watt, 2013). Thus, this stimulus further supports the expectation of adverse emotion processing in right hemisphere of the brain.
Effects of environmental conditions
For this stimulus different environmental were tested in numerous studies and diverse results were found. Some of results found were contradictory to each other. The first stimulus was tested empty viewing area at the end of tunnel in a bare
One study startled fish by shaking the frame on which aquarium was placed, this startle simulated a large wave or displacement of water by the presence of large predator. For results their orientation was recorded whether they were oriented left or right after startle (Heuts, 1999). For this startle test fish indicated right side bias (Heuts, 1999). Another startle test conducted on zebrafish found similar results, and fish were startled by turning off light quickly (Watkins et al., 2004). Study was conducted in a compartmentalized set up, and light were turned off quickly urging fish to move in next lit up comportment through a small vertical opening and their initial turn was recorded (Watkins et al., 2004). In the result of this an overall right side turning bias was