These are Melanotaenia sp Williams Creek (Melanda Rainbowfish). I'll do my best to include two trios of young fish (males are just starting to color up). They were spawned in my fish room this past winter in hard suburban water. This species is traded and kept by Rainbowfish enthusiasts and isn't generally available except from another enthusiast. In the wild the Australian government considers this species critically endangered due to habitat loss and interbreeding with other Rainbowfish species. Check out the Reference link I've included above for details in the effort to keep these fish alive in their native habitat. It's a small Rainbowfish who gets along with others as long as there aren't too many males in the group. Like many Rainbowfish, males can pester the females to death if the ratio is too skewed towards too many males or there isn't a place for the females to hide and get a break. Though small, a 2' long tank should be considered a minimum. Mine are more orange than the photos in the article and some other photos on the internet. This is a MAS BAP donation.