The genus Koumansetta in a reef aquarium

There are 3 species in the genus Koumansetta; I have had two of them but with very bad luck. In 2014 I get 8 Koumansetta rainfordi to my old Aquarium of 450 L They did not really go well – they did not start to eat and slowly disappear from the aquarium. I decide to stay away from these beautiful fish. When I was able to get two Koumansetta hectori that have been in a 10 000 L aquarium for over 2 years to my new aquarium in 2019 - I decide to give the genus a try again. This time – there was no problem with food and eating but after 4 months they just disappeared. It looks like they slowly just fade away. Someone have said that these fishes are very depended of algae. As an aquarium fish – they are very attractive, small (around 8 cm as largest) friendly and beautiful, however – at least for me – it is sensitive fish. I have seen that at least one of the species have been cultivated in captivity, I think it was K.rainfordi. Maybe I do a new try with some cultivated individuals. In the 10 000 L aquarium where my former pair come from – there was a lot of hiding places there these small fishes could dominate and live their lives – so if any decide to try them – let them be the main character in the aquarium Sincerely Lasse