Four-eyed fish are very challenging fishes, and unless you have a tank specifically for them, they are best avoided.
As a baseline, what you need is this: a brackish water (SG 1.005-1.010) aquarium with maximum surface area. No less than 12" by 48" in width and length. In the centre of the tank you need a flat slate (or similar smooth rock) resting on a couple of flowerpots so that it makes a little "table". The water level needs to just cover this table, so the fish can lie on their bellies there with their bodies covered in water but eyes poking above the waterline. You need some space above the waterline and a tight-fitting lid because they can jump very well.
When settled in, these are fabulous animals, and in good condition aren't especially delicate. They eat most anything, but like insects and floating pellets best. The main problem is settling them in, and when kept in freshwater tanks they lose conditions rapidly.
Cheers, Neale