Debate on large fish and crayfish eating smaller fish.

[stingray4540]

Obviously, fish will eat anything that fits in there mouth. But, why would a fish/crayfish excert unnesesary energy to catch it's food when it's hand fed to them on a regular basis. Consider public aquariums, You often see fish kept with there natural prey, yet there never seems to be a problem with tank mates getting eaten. This I believe is because they know they are going to get an easy meal at the same time every day/week.
So, the debate is:
If preditory fish/crayfish are never fed live fish, and are fed well on a regular basis, would they still be inclined to eat there tank mates?
I hear a lot of people saying no! you can't keep large fish/crayfish with other fish small enough to fit in it's mouth, but every time I visit the public aquarium, I wonder why the sharks don't eat all the smaller fish swimming right in front of it's nose. So, my vote is: it is possible to keep small and large fish if you never feed live fish and keep them well fed.
Please, only logical arguments, don't reply just because "that's what you've always been told"

 

[ohbly]

Most of the sharks kept in public aquariums are species that prey on sick or injured fish. When they sense that a fish is in trouble they get excited and switch to feeding mode. Im sure that if any of the smaller fish that swim by the sharks noses showed any sign of distress it would be quickly eaten.
If they put a shark like a mako in a public aqarium nothing would be safe.

Iv kept foot-long goldfish with mountain minnows in a pond and they showed no interest in eating them, even the minnow babys barely 10mm long were safe. It wasnt because they had never been fed live food before as I fed them live mealworms.
I also had a male paradise fish that lived outside and he wouldnt eat any live food he shared his home with waterboatmen and water beetles which ate the mosquito larva as the fish wouldnt eat them. He would only eat pellets that he plucked from my fingers. Why? I do not know

To answer your question is it possible? yes
but is it predictable? no

 

[Raskolnikov]

If preditory fish/crayfish are never fed live fish, and are fed well on a regular basis, would they still be inclined to eat there tank mates?

Yes, IME. Even piscivorous fish that I've raised from eggs in my home and are never offered live food will turn on and eat their tankmates.

 

[Kissofthegorami]

Try putting anything with claws in with your fish.

 

[chinnp]

I would say yes. Well-fed or not, it's in their nature to prey on other fish. Most sharks in aquariums are kept with fish that can swim far faster than they can. The sharks don't chase them because they've tried it in the past and have had no luck catching them.

 

[Roan Art]

Depends on the individual.

I've a blue lobster (procambarus, not cherax) that has never harmed any fish he's with. In fact, I've seen ALL the silver dollars gang up on him and steal his algae wafer. He lifted his claws to try to ward them off, but didn't open them. I gave him a new wafer

The dollars range from 2" to 4½" in size. The blue lobster is 5".

Roan

 

[stingray4540]

Well, sharks were just one example and are not the only preditory fish kept with there natural prey. And btw, I've seen seven gill sharks, black tips, and young makos in the aquariums near me. In fact, one of these aquariums was just recently the only aquarium so far to succesfully keep a great white in captivity, It was recently released back to the wild though.
And yes, the reason I posted this is because I am considering adding something with claws to my tank. In everything that I've read so far, it seems like the people who have actually kept crayfish(like roan here) have not had problems with them, and everyone else, who don't give any examples of experience, say that it can't be done.
Also, in the future I was going to try an expariment with raising some large sa cichlids, such as oscars or dempseys with some smaller fish and see if they look at them as food when they are big enough.

 

[Roan Art]

If you try it, stingray, make sure you don't try it with cherax sp.. crays. I've had both. While the procambarus I have is mild mannered and easy going (which is what they are said to be, overall), the cherax I had was a bloody destructive devil. Not only did he harass and go after my fish, but he THREW stuff around in the tank. He moved the heater several times, pulled the intake off the filters, moved rocks, plastic plants, you name it. He also ripped things apart.

He even caused his own death. I had built a cave for him out of some heavy pieces of rock that I thought he couldn't move. I was wrong. He pushed the wall out and the whole thing fell on him and smushed him good.

Just be careful what you buy. IME you'll have a better chance of getting a good cray if you stay away from any cherax.

Roan

 

[stingray4540]

In the words of Red Forman: "Dumb ***" (from: That 70's Show) :laugh:

 

[daveedka]

My experience has been that the instinct is ingrained deeply. I have had several Oscars who never saw live food in the first 2-3 years of their life and didn't hesitate more than half a second when a feeder of some sort was added. My experience with clawed critters was not good, and therefore It was limited to one attempt. The Crayfish (sold as an Australian Blue lobster but I doubt it was) Was added to a tank with large fish. In two days he shredded every fin in that tank while trying to eat fish twice his size. eventually he ticked off something bad enough to get himself smashed. I haven't experimented since.
Don't know if that will help, but that is what I have observed.
Dave