I heard some piranhas were vegetarians. Does that mean some other fish can eat meat and plants at the same time? Is this a common thing?

Hi Joon,

Fish, like many animals, contain species that only eat meat or only eat plants as well as species that will eat both meat and plants. The fish we usually keep as pets tend to eat either plants or both plants and meat. This is because meat-eating fish would require us to continually feed them with other live animals, which is a bit cruel outside of a wild setting.

Generally meat-eating is easier as you are converting muscles, bones and other body parts into muscles, bones and other body parts! It is much harder to get nutrition from plants without a lot of processing - this is why, for example, cows have four stomachs or why rabbits will eat their own poo (so the food passes through their digestive system twice).

So yes, it does happen and it is quite common!

Last edited by Graeme Lloyd (24th Feb 2007 18:04:25)

I thought it might be of interest to add in that despite the piranha's fearsome reputation, most of the speices of piranha in the Amazon are in fact omnivorous (they can eat both plants and animals), and feed on a variety of seeds, fruit, leaves, snails, insects, and meat.

Having a wide ranging diet is clearly an advantage for an animal, because it will be able to make use of more opportunuities when it comes to getting its dinner, and will be less likely to be affected by any changes to its habitat that alter its food supply.

Last edited by Phil Jardine (25th Feb 2007 12:53:41)