You just need a surface orientated soft-water fish that doesn't eat the fry. As well as Marbled Hatchets (Carnegiella strigata) or Hockey Stick Pencils (Nannostomus eques) etc., if you don't mind which continent they came from you can use Rocket Killi (Pseudepiplatys annulatus) or Threadfin Rainbow (Iriatherina werneri).Then what would you suggest using for dither fish