funnily enough I was writing an essay about hybrids earlier
The problem with hybridisation is that it ruins the genetic stock (if that makes sense). Say, you had a lion and you bred it with a tiger you'd get a Liger (or if the male was a tiger, a Tigon), which is far less than diserable as it has no benefit to either species.
Now, I bet you're thinking that this has nothing at all to do with fish!! Well, lets take a look at a few points on Ligers & Tigons and compare them with fish.
#1:
Both have extremely different growth rates - ligers tend to be "giant" cats, reaching up to 12ft high when stood on the back paws whilst tigons tend to be dwarfed.
How does #1 affect fish?
as you can see with the ligers and the tigons, hybrid species in general can vastly differ in size. So hybrid fish may turn out to be three times the size of the parents!
#2:
Ligers have been spotted to have moments of conflict between the personalities of the two mixed species, having mini-mood swings so to speak (eg: Tigers are very keen swimmers and love water - whilst lions are the complete opposite. Most ligers tend to argue with the two species they're bred from and have difficulty overcoming obstacles that one species is adept at and the other isn't).
How does #2 affect fish?
All species of fish have different personalities and breeding two different species together can cause a personality "clash" in the offspring, making its behaviour difficult to predict and may cause it to be more difficult to care for.
#3:
To date all male ligers and tigons have been proven to be infertile which would prevent them from spreading their genes, females however are not and can be bred with both lions and tigers to create li-ligers, li-tigons, ti-ligers and ti-tigons.
How does #3 affect fish?
Wether male hybridised fish are infertile I do not know but as the females probably would be they could further ruin the genetic stock.
Thats enough of me going on about ligers and tigons
another point that you may want to think of in hybridised fish is that theres not a lot of call for them - unless you got another tank you may have a pretty hard job giving them away once they're old enough.
For the record, if I've made any really wrong points here feel free to correct me
