Based on this information, what is this fish's phenotype for the body color trait?

 - a greenish-brown body
 - a pink body
The Nile tilapia fish's genotype for the body color gene is BB. The Nile tilapia fish's genotype of BB has only B allelles. The B allele is for a greenish-brown body. So, the Nile tilapia fish's phenotype for the body color trait must be a greenish-brown body.
To check this answer, consider whether the Nile tilapia fish's alleles are dominant or recessive. The allele for a greenish-brown body (B) is dominant over the allele for a pink body (b). This means B is a dominant allele, and b is a recessive allele.
The Nile tilapia fish's genotype of BB has two dominant alleles. An organism with at least one dominant allele for a gene will have the dominant allele's version of the trait. So, the Nile tilapia fish's phenotype for the body color trait must be a greenish-brown body.