Next suggestion is move these two to suitable or confirmed good pond spawning species. There is one local pond near me that is 'full' of central mudminnows. Mudminnow has been published in a journal to be a good species for forage for yellow perch in ponds, small lakes. But I'm not sure how well it would withstand bass predation.
Umbra limi (central mudminnow)Commercial sources: Jonah's Aquarium special orders
"Commonly found in slow moving streams, creeks, drainage ditches, and ponds with abundant vegetation and bottom layer of organic matter." [ref]
"They inhabit both lotic and lentic habitats, providing that the waters are still or slow moving and there is dense cover available." [ref]
http://www.nanfa.org/fif/mudminnow.shtmlUmbra pygmaea (eastern mudminnow)Commercial sources: Jonah's Aquarium special orders
"Inhabits quiet streams, sloughs, swamps and other wetlands over sand, mud and debris, often among dense vegetation." [ref]
"The typical habitat of U. pygmaea is lowland waters with little to no streamflow, such as backwaters, ponds and irrigation channels." [ref]
