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If you got carni/omnivorous fish to spawn, then took away the fry and raised them to a decent size, would the parents eat them?

Would this depend upon the parental skills of the fish and how long would the sepsration have to be?

Note: hypothetical question

Hi,
The answer is Yes, the parents would eat them.
Once the fry are free swimming they no longer need
parental care and the parents who have generally not
eaten during that spawning and nurturing time, will
then begin to eat the fry.
If you remove the parents and then bring them back
they will eat the fry.
If you leave the fry in the tank long enough and they are
free swimming, the parents will begin the spawning
procedure anew and then the fry represent a threat to the
new eggs, and again will be eaten as a protective measure.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Ultimately, it depends on the species of fish.

Oh, you've opened a BIG can of worms here.

Most fishkeepers will be thinking at this point of the word "Cichlid". Because Cichlids are the archetypal advanced fishes as far as parental care is concerned.

In the case of Cichlids, removing one batch of fry would probably result in the appearance of a second batch of fry soon after. Mixing in the original batch of fry after that could prove interesting, not least because several authorities in the world of Cichlids (Ad Konings, Dr Paul Loiselle etc) have reported instances of Cichlids not only taking on board the fry of other parent Cichlids in the wild, but taking on fry of other Cichlid species as well, in an interesting strategem that involves using the co-opted fry as an 'outer shield' for their own fry ... there are quite literally endless possibilities for what could happen here.

Other fish Families, well, the results would be mixed. Chances are that if you ever managed to spawn one of the members of the Family Erythrinidae, then you would have to keep the fry separate from the parents from the word 'go' because these fishes will snap at anything that moves ... which in the case of larger ones includes the aquarist's limbs! If ever you're in a position to afford to keep Hoplias lacerdae, for example, and attempt to breed it in the aquarium, you would have to keep the fry segregated from the parents, and pretty soon you would have to segregate the fry by size, because the larger ones would eat their smaller brethren in fairly short order, which gives you an idea what you would be taking on with that beast ... this photo]http://www.rochauruguay.com/tarariraventura/images/Tra%EDr%E3o%20300.jpg[/link] should give you an idea what you would be taking on with that fish, and a big one would probably be capable of amputating your arm at the elbow ... more pics of this beast can be found [link=here]http://darwin.zoology.gla.ac.uk/~rpage/ispecies/?q=Hoplias+lacerdae&submit=Go[/link], with a particularly good look at the car crusher jaws of this fish [link=here.

An interesting exercise for you, should you be willing to try it, is keeping and breeding Belonesox belizanus, a predatory livebearer - this will breed in a manner analogous to that of the familiar Guppies and Mollies (because it belongs to the same Family) but you'll have to supply it with a LOT of live fishes to condition it for breeding, as it will eat precious little else once it's over 3 inches long. You'll find the fry are ravenous little so-and-sos too ... again, the bigger ones will eat the smaller ones if you don't sort them for size. Put the fry in with the parents 14 days after birth, and chances are the parents will make a snack of them without too many worries about the morality of eating one's own children ...

So, given that you have something like 3,000 species of aquarium fishes that could be considered at least partially predatory, you will have fun working out which ones do what.






Panda Catfish fan and keeper/breeder since Christmas 2002

When i started this thread i was thinking cichlids. Could prolific breeders such as convicts survive on their fry as a live food? Also, when fish are territorial because they aere breeding, do they eat other fish or just harras/kill them?

With Cichlids, you have a range of possibilities.

In the wild, fishes such as Herotilapia multispinosa and Neetroplus nematopus engage in what might be termed 'Pavlovian conditioning' of the other fishes in their home waters. Accompanying the vivid colour changes are changes in behaviour - the parent fishes basically launch attacks on fishes that come too close to the spawning ground, and the other fishes learn very quickly indeed to stay away.

Behaviour might be different for something that is a determined predator such as a Parachromis Guapote though. It's possible that a big Guapote might kill and eat certain classes of intruder, but I haven't seen reports of this behaviour occurring in the wild.

The reason why big Cichlids become killers in aquaria is because, in the wild, the fishes that they chase away have ample space to escape. In an aquarium, this isn't the case, and the pursued fish can find itself being subject to constant harassment, which results in stress, either directly because of physical injury, or indirectly because of the pressure of being attacked by something big, powerful and muscular with a determination to protect its young. That's why, if you want to keep the peace, you house big Cichlids in VERY spacious quarters, or better still in the case of things like Jaguar Cichlids, give the breeding pair their own exclusive aquarium in which to breed.

There are some creatures, however, that Cichlids will attack and kill on sight if they find them too close to the eggs or fry. Dragonfly larvae and water beetles fall into this category. Consequently, way back when Innes was writing his venerable tome, he recommended that these creatures be used to provide live food for parent Cichlids. The Cichlids, upon seeing them, recognise them as a threat to the fry, and immediately go into hunter-killer mode. This provides the parent fishes with double satisfaction - exterminating an enemy of their young, and satisfying their appetite with a nice crunchy treat.

So, if you acquire a breeding pair of big Cichlids, drop in a couple of Dragonfly larvae, and watch the big Cichlids wolf them down with gusto. They'll do that even outside the breeding season, but if they have fry to protect, their willingness to destroy such creatures multiplies considerably.

Use of such measures helps keep the peace in addition with fishes such as Black Belts, that are notorious for murderous divorces because the male's instinct to attack fry threats is so great, that sometimes he attacks the female. Give fishes such as this a diversionary focus for their very strong defensive instincts and they'll be less likely to turn on each other.

Be careful to choose prey creatures matched to the size of the Cichlids though. For species such as Convicts, Salvinis or the demon Neetroplus nematopus, Damselfly larvae are more appropriate because they're smaller. Adult Dempseys and larger Cichlids (Oscars, Black Belts, big Guapotes) will handle Dragonfly larvae and even large water beetles with ease.

One fish that probably WOULD eat other fishes that came too close to the fry is the Wolf Cichlid, Parachromis dovii, because it's a serious predator. But then most people who keep those have them in a species aquarium because of their sheer size - a full grown male dovii is a 30 inch fish, and moreover in the wild preys on other smaller Cichlids! It's recorded in the wild as being a major predator of Neetroplus nematopus among others (Dr Paul Loiselle cites this behaviour in his Cichlid Room article on Neetroplus nematopus). So don't put your Neets in with a dovii or the dovii will thank you for a tasty and expensive snack.


Panda Catfish fan and keeper/breeder since Christmas 2002

Interesting thread. Sorry to crash it, but my questions is related. Here's the scenario. Dad krib has been banished to another tank, due to him turning on mum. Mum remains & is guarding her at least 2+ week old fry. I thought the fry would be safe forever with mum, particularly if dad is not there (so no chance of another spawn that she may need to protect from her first brood).

Will I need to rethink my plan of leaving fry with mum indefinitely?

Cheers
TW

Probably not. Chances are the female fish will, when she is ready, start dispersing the fry. However, this will probably not take place until the fry are about 6 weeks old, and well able to fend for themselves. This is the typical wild scenario, and is replicated frequently in the aquarium.

However, if the fry are removed early, parent fishes start spawning again.

Of course, matters are complicated in your case by the fact that the male has turned out to be a less than optimal parent. However, there may be reasons for this. Some Cichlids have very strong defensive instincts, and in the absence of a real threat to the fry, mistakenly focus upon the partner when operating in 'attack mode' (certain large Cichlids such as Black Belts are notorious for murderous divorces of this kind, as are Julidochromis species from Lake Tanganyika). It's possible that the way forward here is to give the male an alternative focus for his defensive instincts - some dither fish, or some nice Ghost Shrimp to attack.

I've already posted in the Cichlid section of the Board on numerous occasions how the venerable Innes book recommended using critters such as Dragonfly larvae and water beetles to act as a focus for parental Cichlid defensive instincts, providing the additional satisfaction of a crunchy meal into the bargain. Of course, the size of critter should be matched up with the Cichlid in question - Convicts should me matched up with Damselfly larvae because they're smaller, while dragonfly larvae are suitable for Dempseys upwards.

If you can find some suitable 'target critters' for your Kribs, it's possible that the male may, upon venting some steam upon the target critters, be more amicably disposed toward his lady.


Panda Catfish fan and keeper/breeder since Christmas 2002

Thanks Calilasseia,

I think the male has been removed for too long now, to return without eating his fry while they are still small. He has been banished for around 10 days. I like your idea about Dragonfly larvae and water beetles, but don't even know where to begin to find them. Absolutely certain no-one around here sells them.

When fry are 6 weeks, will they be big enough for him not to eat? My goal here is to watch this current batch grow to adults, not to breed a new batch before that time?

Cheers
TW

At 6 weeks they'll be too big to eat, or should be. If they grow at the typical rate, they should be approaching 15 mm SL, which should be too big to swallow. Whether they'll be safe from being harassed is another matter though where Dad is concerned ...

In any case, if you're intending to raise a decent batch of fry to saleable size to take to a store, you'll be looking at rehousing them soon anyway to grow them on.


Panda Catfish fan and keeper/breeder since Christmas 2002

Thanks again. Is there a reason though, why I can't grow them on in the tank with mum? It is a 23G tank, just with 2 otos, mum & her fry? My plan is to grow them on in there, where they are. Wouldn't that be ok?

Thanks again.

Cheers
TW

Hard to say. Kribs are highly territorial and will snap at other fish in the vicinity, genetically affiliated or not.

After 6 weeks chances are Mom would start chasing the babies away. Which she would do in the wild to prepare for the next batch of egg laying and fry rearing. From that point on you would NEED another rearing aquarium, either that or you would have to rehouse Mom and let the fry continue growing in their existing home.

Welcome to the wonderful world of Cichlid raising.


Panda Catfish fan and keeper/breeder since Christmas 2002

Ok thanks, I'll leave them together for as long as it still works & if anyone moves out, it will be mum. Easier to catch one fish than about 35 fry in a heavily planted tank. Easier to accommodate 1 fish into an existing tank too. Thanks.

desiredusername, hope you didn't mind my questions in your thread. They seemed to relate to your theme (sort of).

Cheers
TW