Yes, servals eat frogs and fish. The serval has a preference for wetland habitats and therefore it is unsurprising that they hunt in water and don’t mind getting their feet wet (Wild Cats of the World).
Captive servals deftly hook live fish out of water and in the wild servals have been seen hunting frogs and water birds. One young male was observed to catch and eat at least twenty-eight frogs of various sizes over a three-hour period and an animal shot in Kenya was found to have a stomach full of crabs.
Reference: Rosevear D.R. 1974 in “The carnivores of West Africa” and Geertsema A.A. 1976 in “Impressions and observations of serval behaviour in Tanzania, East Africa”.
P.S. Servals also use vehicle headlights when hunting. They wait for a vehicle to come by at night or dusk and aided by the headlights are able to spot a prey animal that might be crossing the road and bound after it. They settle down to eat the prey by the side of the road.
Other reference for this information: Lousada A. 1956 Rearing serval cats. And also, Scott K.W. Jnr 1980 in “Headlights as a hunting aid for servals in Ethiopia and Kenya.
