Cannibalizing Fish?!?

N

Nanami

New member
So my boss has a fish tank at her desk. She has 2 black mollies, a black balloon fish and two red GloFish.
Yesterday, she also had a white molly as well.

This morning, when she came in, she saw her white molly had died over night. She's kinda squeamish about fishing out dead fishies, so she asked her co-worker to do it for her. When her co-worker fished it out, THE ENTIRE BODY OF THE FISH had been DEVOURED by the other fish! All that was left was the head of the white molly.

These black mollies have been behaving strangely since they entered her tank. They will not eat the flakes she drops in daily or the algae pellets we drop in the tank. They hide behind the plants and inside a large jug decoration she purchased.

Can anyone help explain what the heck is going on?
 
Live fish eating dead fish is entirely normal, all the fish she has are omnivorous and they hold no sentiment for the dead, it's just a free meal.

However, the lethargy, loss of appetite. and the dead fish could be a sign there's problems in the tank. How long as the tank been set up? What size is it? Was it cycled? What are the water parameter readings?

It could be that there's a problem with the water quality and it needs a water change and further addressing if the tank is too small/is new and has not been cycled.
 
Easy, Fish fall into 2 main categories, bottom feeders and predators. Bottom feeders are scavengers and will eat anything they find, including dead fish floating. Predators will hunt down other fish fry. Guppies are a good example of a predator. They eat anything. If you look, you will see that fish meal is a major part of most every fish food of any kind, flake or otherwise. What the little fry have to worry about most is mommy hunting them down within moments of being born. That is why there is a special holding tank used by breeders,suspended in the main tank which has narrow slots in the bottom and sides which let the fry swim out while being too narrow, thus keeping mommy confined. MOST fish will eat their own dead or alive, given the opportunity. Strange behavior could be a number of things. More often than not, tank chemistry has gone "off" for some reason. Chlorine in tap water can kill the bacteria in the gravel bed which will cause ammonia and other bacteriological things to poison the tank. Your filter may need cleaning. Replace the activated charcoal while you are at it. Visit your local public library and pick up a book about maintaining a tank in good health. It really is easy. For a number of years, I maintained a 20 gallon guppy tank in an office where I worked. The only regular chemistry I used was a chlorine neutralizer to "treat" the tap water, and a pH adjustment once in a while. We had really good tap water so not much was needed. Other than that, routine filter cleaning every week or two and a small heater was all the tank required. Periodically, I would get a male or two so the tank could repopulate itself. The guppy females (if they get hungry enough) will hunt down the males as they are smaller and less agile than the females, but a male will usually last long enough to breed. Then isolating the pregnant female and soon enough, I'd have a dozen more fry to raise and add to the tank.
 
was the white molly showing any signs of illness if so maybe the illness has been past on from the new white molly to the rest,
or is the ammonia spiking from having a dead fish in there for most of the night try a small water change if they pick up then ammonia is to blame if not then there is a good likely hood your bose put more then just the white molly in the tank (disease)
try not to put to much food in if they are not eating it & scoop out any which has not been eaten.
hope this helps
 
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