Oscar Killing for Fun?

[DonnBallenger]

My oscar normally consumes 2-3 small minnows every few days, so I thought it would be a good idea, since I have a large tank with very few inhabitants to just toss a dozen or so minnows in there every week and let him hunt his dinner like he would in the wild.

At first I started noticing dead, uneaten feeder fish stuck to the filtration system every few days and chalked it up to the fact that they're cheap bait fish. For some reason, my guys won't eat the dead ones, so I'd just dip them out and put them in the garbage. Then I noticed it happening more and more and started worring about the levels of toxins in the tank and thinking that maybe they were dying off first because they're small.

WRONG.

Today I was watching my oscar chase one of the feeders around the tank, doing his usual "Jaws" impression. I really get a kick out of watching him hunt the little guys down....sick, i know. Anyway, he finally cornered the feeder, nipped him a good one, and to my surprise he lost interest in the wounded fish and simply let it die. After I was sure it was dead and wasn't going to be consumed, I dipped it out and exhumed the body of the one I had dipped out earlier this morning from the trash can (gross, i know, but its in the interest of science) and as I figured, he didnt die of natural causes....unless you consider chewed up fins and bite marks natural.

Sorry I'm so wordy, but this actually does have a point. Do a lot of carnivorous fish kill for fun or did I just happen to land the Jeffrey Dahmer of the aquatic world? Should I go back to buying the feeders 2-3 at a time?

 

[trotty]

You are not alone in this fish misery!
I too had this happen on more than 1 occation.
I have had a few oscars in my time and would throw in excess food (live goldfish, crayfish)for them only to turn the lights on in the morning to find most of them stuck to the filter in pieces.
After watching for a while i found the largest and dominant oscar would make it his duty to eliminateall good food before the others were able to get close or finnish what they had,before eating any more...

It's not just Oscars either, my saratoga does the same. I dont know if its terratorial or just being a pain in the bum.

In the end i succomb and bought a 50gal to store and breed my feeders.

PS have you thought about breeding mice and feeding pinky's? My friends used to freak out when i used to thrown in mice!

 

[JeffreyL]

aggression

I can't speak for oscars, but I have had 2 fish that started killing others in the tank. First was an angelfish that became aggressive, shooing all others to the back of the tank. Then he and the red tailed shark (the only fish in the tank that would not back down) went at it one nite after lights out. Next day I found one dead RTS and a slightly battered angel. Next time was a powder blue dwarf gourami. He grew a small bulge on his head like a parrot cichlid (?) and started getting dominant. Finally he killed some neon tetras and started eying a female GBR. So out he went!!!!!!

To answer your question, it appears some carnivorous fish (and some herbivores) do become homicidal. In both of my cases, the aggressor was, or believed himself to be, the dominant fish in the tank, and it went from there. In a more balanced setup, all might have been okay. Or not. All fish are different. Listen long enough and you will hear of a sweet tempered Auratus and a killer discus. lol

 

[BrianNY]

This is JMO for the health of aquarium fish.

There are a few species that will only consume moving prey. Oscars are not one of those species. Offering feeder fish is a risky proposition. They are often kept in the poorest of conditions and as a result will harbor some very nasty diseases. It's only a matter of time before some illness is transferred to the fish you are feeding.

With so many high quality commercially prepared dry and frozen foods available there is no need to use feeder fish. It's a recipe for disaster.

 

[trotty]

I had a good supplier for live foods.... and like i said i bred mice and crayfish.
main diet was the HIKARI Cichlid gold.

 

[malkore]

He kills out of instinct, not hunger. Protecting his tank space.

 

[Guest]

Offering feeder fish is a risky proposition

Agreed. I had Oscars for a long time. I used to love to feed live once a week, and I had a snakehead mind you.

The ones I fed cichlid pellets were ALWAYS heathier in the long run and it is cheaper.

Mix different diets and they will be very healthy. And every few days is quite a lot. If you fed live once a week he would eat them.

If you really,really want to feed live food still, try and breed your own feeders.

These are great--small-medium-large

http://www.bigalsonline.com/BigAlsUS/ctl3684/cp18328/si1380112/cl0/hikaricichlidbiogold88ozmedium


I have seen people say they will not buy any fish from a tank that contains 1 dead fish, but then they buy a dozen feeders from a cloudy tank with 10 dead fish?

 

[Ineubis]

I am having the same issue with my scats now. I bought too many feeders for my Datnoid.

First off, they were supposed to be guppies, but they gave me Rosy Reds instead. My red scats are killing them just to kill them...then obviously the datnoid does not want them.

I'm pulling out 1-3 daily.. only have a few left...

Think I'm gonna lay off feeders for a while...my predator eats like a king on prepared foods as it is.

 

[DonnBallenger]

the feeders i've been buying are crappie minnows. there's a lot of bait stores around here that sell them in bulk for fishermen. i have a few extra 10 gallon tanks and a spare 30 i could use to breed them....but are they difficult to breed?

 

[Menagerie]

I don't think you would have difficulties breeding feeder fish, but I would start with decent stock. Inferior fish produce inferior fry that are prone to disease, even in a home tank.

~moved to the cichlid forum~

 

[clubsuperduty]

I wouldn't feed Oscars feeders I would stick to warm water fish such as Guppies, Mollies, Platys things of that sort feeders or rosys are high in fat being they are a cold water fish and not acceptable staple food for oscars. I personally don't feed mine feeders only live ghost shrimp as treats once a month. You should feed them a staple food such as Hikari gold pellets and I also switch between jumbo krill and ghost shrimp as treats Beefheart is also good in moderation or try crickets but IMO I would stay away from feeders.

 

[ChileRelleno]

I gotta comment on this one...

As already stated...
The O is doing what comes naturally, but he's not hungry so it goes to waste or it is seen as interloper in his territory and is attacked.

I have no problem with feeding feeders...
Properly quarantined or raised by you, and then in moderation.
Feeders should be tropical fish, not cool/coldwater species as such have a much higher fat content. Good tropicals are Guppies, Platies, Mollies, Cons...
Feeders should be a treat, perhaps a couple per week, they should not be a staple food for O's...
The only fish that should have feeders as a staple is a piscivore (primary diet is fish), e.g. Dovii aka Wolf cichlid for example.

Much better than feeders are nightcrawlers, red wrigglers, mealworms and crickets. These are usually available at your LFS/LPS and bait stores.
Wal-Mart carries very nice nightcrawlers and they are one of my commonly offered treats.

DIET
A quality cichlid pellet or stick should make up 75-80% of your O's diet.
These are my primary foods...
Pellets, Carnivore sticks, freezedried krill, algae wafers, fresh nightcrawlers, fresh/freezedried earthworm (Any worms are great foods!), fresh crickets, fresh mealworms, almost any insect I catch (Insects from outside do pose a risk of insecticides which can harm your fish, be careful.).

I rotate store bought nightcrawlers, crickets and mealworms about monthly on the menu.
I feed my 10"+ O probably 4-6 large crickets, 6-10 mealworms or 1-2 large nightcrawlers per feeding and he'll get'em every 2-3 days.

I feed or have fed my O all of these foods...
Raw/cooked shrimp, small bits of raw cut fish, beefheart, bitesize bits of fruits-n-veggies (zucchini, carrot, shelled peas, shelled corn, apple, orange, pear, papya and etc...), small tree/grass frogs (NO toads, and know which frog species your feeding as some can be toxic too.) and properly quarantined or raised feeder fish, these should be fed sparingly and rotated as snacks or dessert.
Do not feed unquarantined feeder fish from LFS/LPS, do not feed mammalian flesh (Animal fats from mammals and fowl are very bad for most fish).

I supplement his nutrition by soaking his pellets 4-5 times a week in a liquid vitamin.
I use Vita-Chem, available at some LFS's and on-line retailers, I get mine at BigAl's, http://www.bigalsonline.com/BigAlsUS/ctl3684/cp19215/si1380216/cl0/boydvitachemfreshwater4oz
Alot of different types and brands are used, Liquid Centrum for example, but you could reasonably use any quality L. vitamin