if your doing your 125 in the same ph, tempature and salinity you can use nets to chase them 1 at a time into a small clean container. Just becareful carrying them to the new tank because sometimes they jump.

if you can keep both tanks running add fish slowly.add three then one every two day is best as it wont put your ammonia through the roof and create to much waste.. i had to take every rock out of my tank to catch them as it took forever trying to do it with them in.. i just catch and put straight in to next tank.. as long as temp and ph is same.. it takes 6 weeks for your tank to build up enough bacteria..

lol i did it the dogy way i just got 3 peole to lift my 55 forward and put the new 180 behind it half filled it then put everything in from my 55 rocks water filter gunk and some more water from my 40gal and added fish at some time every fish lived fine and ammonia didn't realy jump.
sometimes u get lucky

Thanks all!