These are clown fish , there are orange ones and grey ones they live in the sea.
Principle #1- Genetic Variation Some clown fish are orange with white strips and others are grey with white strips. Also, some of these fish grow to be big and some small.
Principle #2-Overproduction and struggle for Survival Clown fish produce many other fishes, they usually produce more that will actually survive since most get eaten by sharks. They also struggle to survive when they have to combat disease and even competition.
Principle #3- Differential survival and reproduction Orange and small fish are more likely to survive since they have a better ability of blending inside an anemones since there where they usually hide. These anemones are mostly of orange fish and yellowish colors that are not that big.
Principal #4- Change in Gene pool Overtime the population of grey and larger clown fish will drop in number. The population of orange and smaller clown fish will increase since they are not gonna be eaten as often. Even though there will not be as much grey/black fishes they will not disappear it will just be rare.
Conclusion Orange with white strips are more often to be seen because they are not eaten often. Black/grey fish are rare because there is not ,any because of their disabilities.