Oryzias minutillus

26. May 2023

There are three tiny Oryzias species in the Mekong River basin of Thailand, Laos and Cambodia, which only grow to about 16 mm in length when fully grown in the wild; animals kept in aquariums can grow somewhat larger because they live much longer here (2-5x as long, i.e. 2-3 years). These are Oryzias minutillus, O. mekongensis and O. songkhramensis.

We have now once again been able to import Oryzias minutillus from Thailand. These tiny fishes are not very sensitive despite their small size. Their care and breeding is similar to that of the currently so popular Medaka (O. latipes), but the food has to be small and the water temperature should not drop below 18°C. In the aquarium it is advisable to give freshly hatched Artemia nauplii two to three times a week. Otherwise the tiny fishes like to eat finely grated dry food, frozen cyclops, microworms etc.

While taking pictures we noticed that there are also some equally tiny bycatch between our O. minutillus. They have a very different head shape and orange dots at the base of the caudal fin, and some specimens have orange stripes on the upper and lower edges of the caudal fin. The similarity to O. mekongensis, which we have been able to import occasionally in the past, is great, but the males have small hooks on the anal fin. This is the distinguishing feature of O. songkhramensis. So we can announce with some pride to have imported this species now for the first time (at least recognized).

Because of the delicacy of these tiny fishes, sorting them is prohibited. Any handling should be kept to an absolute minimum, because the risk of mechanical injury is simply too great. It is best to catch such miniature fish in nets as large as possible and then scoop them out of the net with a suitable container, avoiding contact with air. This way, injuries to the small fish are almost impossible.

For our customers: the animals have code 340053 on our stock list. Please note that we supply only wholesale.

Text & photos: Frank Schäfer