i would try with just a big airstone in a 2 ft tank with about 3m /2fm ratio ,let them settle in feed well then do a big waterchange after a week and pull the plug on the heater over night and see what happens ..dont forget to plug it back in in the morning the airstone in that size tank with a air driven filter should create enough current but if not you can always replace it with a small powerhead if preffered but i would think that an airstone will help with oxygen saturation levels aswell and this could help trigger them