Fish becoming land-dwellers today

[mfb]

And we can watch different related species at different steps in the transition. In this case, the reason is not the availability of food, but the lower number of predators on land.

Article

At low tide, blennies are commonly found swimming in rock pools around the edges of the island. But when high tide moves in, they climb up to dry land and shuffle around the rocks until the tide retreats. The researchers found that this is most likely to avoid predators that swim in with the rising tide.
[...]
In fact, several species of blenny fish at Rarotonga and elsewhere have already made the full transition to land-dwelling species. They continue to breathe with their gills, but have developed stronger tail fins that allow them to jump from rock to rock.

Other fish families have also crossed the land-water interface over the last 400 million years – about 33 families in total.

 

[dkotschessaa]

Great job little blennies! Keep it up and you'll be monkeying around in no time!

 

[BillTre]

I find fish in these kinds of zones fastenating and have kept a few species of them, although it is more difficult to provide a shoreline with brackish water (mix of sea and freshwater) than just setting up a salt water or freshwater fully aquatic aquarium.

Mudskippers: well adapted to spending a lot of time out of the water.

Anableps (AKA four eye fish): generally inhabit very shallow water, have eyes with specialized optics to see well above and below the water at the same time. These are livebearers that were thought to be either right or left handed sexually, but that was shown to be wrong.