Field experiment on effects of predation on male guppy colouration

For the greenhouse experiments, Endler constructed 10 ponds designed to approximate pools in the streams of the Northern Range in Trinidad. Four of the ponds were of a size (2.4 m X 1.2 m X 40 cm) typical of the pools inhabited by a single pike cichlid in smaller streams. During the final phase of the experiment, Endler placed a single pike cichlid in each of these ponds. The six other ponds were similar in size (2.4 m X 1.2 m X 15 cm) to stream pools in the headwaters which contain approximately 6 Rivulus. Endler eventually placed 6 Rivulus in four of these ponds and maintained the other two ponds with no predators as controls. What did Endler create with this series of pools and predator combinations? These three groups of ponds represented three levels of predation: high predation (pike cichlid), low predation (Rivulus), and no predation.