Hunters should be able to tame a fish.

[Tsuki]

Not just any fish though.
It has to be strong, fast, vicious... capable of living on land...

SNAKEHEAD.

These fish are pretty much everything a hunter pet can be. In real life, they're very invasive and detrimental to ecosystems, and as such, they'd be like an opposite of the daily pandaria million-fish-pool and large fish pool thing; there'd be less pools and a few of these guys around, ready for taming or killing, the later most likely for some reward (and hopefully non-daily linked ones for taming). It'd be cool... O:

[Zhinru]

There's this "barramunda" concept art that was supposed to be used in Cataclysm, but never was. It may come back one day. It's a land fish if you don't know, and it would hopefully be tamable.

[Equeon]

There's this "barramunda" concept art that was supposed to be used in Cataclysm, but never was. It may come back one day. It's a land fish if you don't know, and it would hopefully be tamable.

Looks like a land Dunkleosteus. Here's hoping that it'll return in the next expansion!

[GormanGhaste]

And of course, we need to be able to tame Starving Amphibious Sharks!

[azurelith]

I must be a geek because this is the first thing I though of when i saw that picture
"If that becomes tamable I will have to name mine Coelamon." <3 Digimon

[ashdawn]

I think it would be epic if they magikarped around and splash to do damage.

[Bulletdance]

And deep sea murlocs....sure ok they might be sentient humanoids, but come on there can't be too many brain cells in there and they're cute!