February 24, 2004

8:32 AM

Can fish interbreed like dogs? My SO and I have been talking about dogs lately so the mixed-breed thing has been a regular topic of conversation. Last night we were at a Thai restaurant with a large fish tank and some gigantic fish. Too big for the tank, in my opinion. And that got me to wondering....can different kinds of fish, genetically speaking, be bred with each other? Even if they wouldn't do it on their own (mating rituals, etc.), could they do it with a scientists help?
posted by jaded to (8 comments total)

As wacky as it seems, all dogs, from poodles to greyhounds are all one species - Canis familiaris.

This is not true for most fish. They are in general, separate species and cannot be interbred anymore than dogs and cats can be interbred. This doesnt mean that fish breeding is not a popular thing, it is, but it is kept within a particular species.
posted by vacapinta at 8:48 AM on February 24, 2004

If I recall, the definition of "species" is subject to one of those great big rollicking debates without end--kind of like the definition of "art."

Setting that aside, there are cases of aquarists creating, through breeding, entirely new breeds/species/varieties of fish. The Blood Parrot Cichlid is one example.

Back when I owned a carnivorous fish, I remember being given a bag full of "mutt fish" as feeders by a friend. I forget their lineage, but I think they were at least half guppy.
posted by profwhat at 8:56 AM on February 24, 2004

If I'm not mistaken, a "splake" is a cross between the (already closely-related) salmon and trout. But I know that, in general, cross-breeding (even natural cross-breeding) has been known to decimate salmon populations and their genetic pool. I believe that fishery biologists take active steps to prevent cross-breeding between hatchery-bred fish and natural populations.
posted by jpoulos at 10:21 AM on February 24, 2004

I have African Cichlids that cross bred in my tank. I think the parents were probably from the same genus, but different species. Like profwhat said, I think that taxonomy, esp. in Cichlids, is more of an art then a science.

I talked to a guy at the local aquarium shop - he said that this type of hyrbidization doesn't usually happen in the wild, but will happen in an aquarium when there are no other options.
posted by drobot at 10:43 AM on February 24, 2004

Just to derail, I'm so disappointed that fishfucker hasn't replied. His knowledge of pisicne interbreeding should be invaluable...
posted by Pericles at 10:57 AM on February 24, 2004

most biologists consider two groups that do not interbreed to be two species, regardless of whether they could genetically interbreed or not. Two fish might mate at different times of the year in the wild, and so never interbreed, these would be 2 species. but in an aquarium with no sense of season they may interbreed.

this separation of breeding times is called temporal speciation. It is a very easy way for species to diverge, as the two species stop interbreeding over millions of years, (or less) they can eventually become so genetically divergent that they could not interbreed if they tried. There are other modes of speciation too that could cause two groups that are genetically compatible to not interbreed: behavioral (mating behavior), allopatric (physical seperation) etc

but like vacapinta says, most fish are too genetically divergent already to mate.
posted by rhyax at 11:14 AM on February 24, 2004

i had to show up in this thread sooner or later.
posted by fishfucker at 1:16 PM on February 24, 2004

Trout rarely interbreed between species in the wild, but hatchery reared trout may be crossbred by squeezing out semen and eggs and mixing them together. These are infertile, useful in case you are not sure of the eco-impact of introducing a fish into a new lake.
posted by zaelic at 10:42 AM on February 25, 2004