I have a pair of common Kribensis (plus a spare male) that are incredibly colorful and spawn incessantly. They are in a tank where their fry are delicious snacks for the focal inhabitants. Should anyone want to try their hands at keeping and spawning these endearing fish, let me know. $10 for pair plus spare. If it weren't going to take me several hours and a partial tear down to catch them, they'd be free.