I don't like to bear bad news
but I have major reservations on your proposed combination:
The venom may not be fatal to humans, but to a small fish?
I have kept a waspfish in the past and I currently own 2 barbarus mudskippers and to be honest I wouldn't keep any fully aquatic fish with mudskippers. The reason being is that mudskipper tanks should have a lot of land and not much water (I would say at least 50% land). They also don't like the water to be very deep - my barbarus tank is approximately 10cm deep and Indian Mudskippers are smaller. Could you keep a tank with very little water in the prisitne conditions required for fully aquatic fish?
Waspfish are very slow feeders and very difficult to train onto anything other than live foods; mudskippers absolutely love their food and get very excited at feeding time.
Mudskippers also crash around their tank (especially if more than one is kept) and my guess is that they wouldn't see the waspfish and consequently get stung or they would scare the waspfish so much that it would never come out of its hiding place to get food and would ultimately die of stress or starvation).
What I'm trying to say is that you would need to have an extremely large and long tank to even attempt keeping fully aquatic fish with mudskippers and it would need to be even larger still to keep a waspfish with them.
If you do attempt to keep a fully aquatic fish then please try it with a more robust fish and a large enough fish so that it wont be made breakfast.
As a final word on Waspfish: I have a couple of theories on why my waspfish died and one of the theories is that it was bullied to death by a halfbeak, the other is that i couldn't provide a balanced enough diet as he would only eat live brineshrimp, daphnia and bloodworm. I believe that these fish should only be kept with very peaceful and docile tankmates.
If you want an expert opinion then try PM'ing Nmonks (he is a mentor here) as he has wrote a book on Brackish species and so is very well placed to comment.
