Answer:
25%
Step-by-step explanation:
This cross involves a single gene coding for spot color in beta fish. Green allele is C while the blue allele is c. This gene exhibits co-dominance, hence, an heterozygote beta fish (Cc) i.e. combination of both alleles, will have both phenotypes expressed to form a green and blue spotted beta fish.
If two green and blue spotted beta fishes (Cc) are crossed, each beta fish will produce gametes with C and c alleles. Using these gametes in a punnet square, four possible offsprings with the following genotypes will be produced: CC, Cc, Cc and cc.
C c
C CC Cc
c Cc cc
Hence, the percentage of offsprings expected to be green (CC genotype) is 1 out of 4possible offsprings i.e. 1/4 × 100 = 25%