food availability also influences the epigenetic mechanisms driving growth rate in the mouthbrooding cichlid, "simochromis pleurospilus". when nutrient availability is high, reproducing females will produce many small eggs, versus fewer, larger eggs in nutrient poor environments. egg size often correlates with fish larvae body size at hatching: smaller larvae hatch from smaller eggs. in the case of the cichlid, small larvae grow at a faster rate than their larger egg counterparts. this is due to the increased expression of ghr, the growth hormone receptor. increased transcription levels of ghr genes increase the receptors available to bind with growth hormone, gh, leading to an increased growth rate in smaller fish. fish of larger size are less likely to be eaten by predators, therefore it is advantageous to grow quickly in early life stages to insure survival. the mechanism by which ghr transcription is regulated is unknown, but it may be due to hormones within the yolk produced by the mother, or just by the yolk quantity itself. this may lead to dna methylation or histone modifications which control genic transcription levels.