I got mine from river wonders because I paid for 2 gatf and never got it from them so after 3 months I just took a bunch of fish from them including the aripima. Watch out for the they are shady!!!!!!!
I bought 2 Gatf from river wonders which were not goliath, so they promised me 2 pimas and they kept telling me they would get it in 2 weeks for about 3 months. When I finally got them they were only4" and died in a week. Riverwonders is super shady. Do not buy from them!
And yes you can keep a arapima in a 125 temporarily. Im tired of everyone crapping their pants when some one asks about keeping a monster fish in a medium sized tank when they are still young. Ask everyone with a dovii, umbie, armatus, or gaft what size they keep their fish in. Even ask em what size is their biggest tank, and I bet more than half cannot house these fish to these impossible standards, and so what.