Discus ate Corys eyes... their EYES

[GTOAviator]

For a couple months now I've held 6 discus in a 55 gallon tank (350 gallons/hr) with 6 little Sterbai Corys and 1 dark zebra. They all went into the tank together and acted completely indifferent to eachother... until today. I got home from work to immediately find a Cory listing on top of a log with his eye gone and some torn up fins. I wanted to believe it was some sort of weird bacterial infection, until I saw 2 other Corys also missing their eyes. Then I caught one of my red dragons in the act - quietly slithering down to the Cory before going for their eye. Fortunately, this Cory was able to get away. However, the Corys that weren't so lucky look pretty messed up - they just sit in the corner of the tank or hide in the logs and don't seem to be eating :/

My question is what changed? Do Discus randomly acquire a taste for Corys?

The good news is the Discus seem quite content. They all seem to be growing fast and their appetite is strong (obviously).

[John_Nicholson]

They are animals, it is what animals do.

-john

[Ryan]

Discus are cichlids. They will definitely go after smaller fish if they are bored/hungry/curious. They won't all do it but it's certainly not out of the question. Unfortunately your cories will probably need to be relocated because I doubt the discus will stop now.

[GTOAviator]

Well yes, I know that they are cichlids and the way of the wild, etc.. but I found the immediate behavioral change strange and wanted to know if something could be causing this? I had heard that Cories are a great tank mate for Discus, despite their slow bottom dweller movement. I have also read that Discus can become aggressive towards other fish species, especially smaller fish - but jesus - their eyes?

[Ryan]

A lot of fish aim for the eyes or fins when they're attacking other fish. Ever had a fish die in your tank? The first thing to go are its eyes.

[Milo2]

Sterbies are great take mates. Personally I think there is a reason as to why this went down. One the Cory's are sending out the "stress" signal. Or you are feeding your discus a low protein diet. Feed them Homemade Beefheart mix with a daily water change and I doubt this would happen. All this...IMHO

[John_Nicholson]

Well is is easier to kill prey that is blind? You first attack the eye's and then you can kill and eat it in your leisure. Probably 20 years or so I came up with the bright idea that I would throw some guppies in several discus tanks. I fugured it would provide a little live food when they had babies. IN one tank they killed and ate the grown guppies, in most of the other tanks the adult guppies were fine but the babies were eaten, in one tank they would not eat the adults or babies. All the tanks were taken care of exactly the same. There was not one tank where stress signals were being send and other where they were not. While they were all animals they were all different animals. Some have more prey drive than others. This is no big deal. It is one animal trying to kill and eat another animals. Nothing in the world is more nature than that.

-john

[discusnutts]

I had a pair of large red turq's that were real killers they would routinely hunt and kill all small tank mates, it was something to watch and they would cooperate when doing it... it was like wild kingdom as john put it.

they would spawn regularly but when I moved them to their own abode they stopped spawning... it wasn't until I introduced small fish to the tank that they started spawning again (oh after a tasty meal that it) so I kept a supply of small feeder guppies just for them.

But that was the only pair I saw do it and once they were out of the orgy tank all the small fish there stopped disappearing. none of the other 16 or so adult discus picked up the habit

[DISCUS STU]

Like most animals Discus follow the law of conservation of energy, as in don't waste energy (food calories), if you don't have to. Discus maybe more than most. How crowded is the tank with 6 Discus in it? You said they're growing well. It's alot easier to get at a live food source of opportunity in a crowded tank.

As in one of the earlier posts, are they being fed enough and also from a good high protein diet?

[jsong]

I do notice my 4" discus's some times chasing my Sterbai Corys, but i notice my golden nugget is some times the aggressor towards other bottom dwellers when they come into his territory.

[bluelagoon]

Just reminds me of the time I first introduced rummy noses tetras to a tank that had never seen an other species.A dozen rummy noses gone just like that.Me standing ,watching in awe with my mouth gapped open.Nothing left except two rummys panting like crazy under the wood.