i have...
5 Tiger Barbs
2 Silver Dollars
1 Rainbow Shark
1 Pictus Catfish

in my tank. i want to put my golden dojo loach in the tank with them because the loach is all alone in a 2.5 gallon tank. is it okay for me to put it in my tank? would does aquarium salt affect the loach?

Yes salt is irritating to the skin of Loaches.You do not have to have salt in your tank.You have fresh water fish.I am sure your catfish is not liking the salt ether seance they of no scales.

The salt would not be good for your loach. It's bad for all the fish you already have too. Assuming your tank is not overcrowded, it should be OK in the tank. Dojos sometimes get hyper and swim up and down the glass in the tank. This might make some of your fish nervous until they learn to ignore it.

I have bred dojo loaches.

I honestly don't know, but why does the tank have salt? I worked in a pet store that didn't have a salt water aquarium, but we had tiger barbs, silver dollars, and pictus catfish, and golden dojos. Those aren't salt water fish.