The Koi betta is often called the Marble betta and is basically a color morph on the common and universally common betta splendens. The Marbled Hatchetfish you at this time come across during the trade are wild-caught, so we advocate quarantining them prior to introducing them towards your principal tank. https://aquariumcleaningselangor.blogspot.com/2024/01/tips-to-follow-when-installing-fish.html