Hi,
I made a mistake when I 1st got a couple of these as I put them in with fast eaters such as Archers/Scats & Monos-so they didn't survive, these have to be in with fish that wont eat all the food b4 these fish 'drift' to it. In the wild they can get up to about 4 inches but in aquaria there size will be more like 2.5 inches, they have a painfull sting so don't touch them. They ARE Brackish fish. I now have 5 but mine at the moment are very tiny, not even 1 inch so they are in a tank of there own until they grow where I will be putting Knight Goby's-Chromids Bubble Bee Goby's in with them as well as Mudskippers & Anableps.
The 1 thing I'm not sure about is if they are safe with Spotted/Figure 8 Puffers as I don't know if the Puffers will harm the Vespicula depressifrons even though they have a sting. To make sure these get to eat just put enough food in all over the aquarium (not over feeding) & not just in one place, I.e Daphnia or bloodworm or defrost frozen blocks & scatter that all over the tank.
If anyone is sure the Puffers will/wont harm these fish please let me know. I'm assuming the Mudskippers (I have a place for them to get out of the water) & Anableps wont harm these!