Good luck with your new discus !! Your 135 looks really nice!! Well done! Now what temp is it at. How the ph? The 25 is small but you could leave them in there for a month changing the water daily and feeding as often as you can and they should grow to about 4” before you add them to the 135. Discus need warm water 84 degrees. So some of the fish you have may not be good with them.