I have had many crosshatches and all did very well after an intense 6+ week QT period. During that time they went through Prazi for internal parasites and Copper for ich. Without treatment, you run a very high risk of internal parasite ensuring the fish will waste away.
My 3" female and 4" male stayed in a 30g for months and really thrived once released. Also, temperature of the tank is a huge factor as these are deep water triggers and need the temp to be around 72-74.