Breeding the Celebes Rice Fish
by Jeff Vander Berg
March/April 2005 Issue #31
I have seen these neat little rice fish numerous times during my career as a tropical fish hobbyist. I have never really gotten around to keeping any. While Tim and I were in Detroit last spring I happened across a bare tank with four very plain fish that I believed had blue eyes on them. I did not know for sure what I was looking at as the closest lights to the tank were at least 10 feet overhead. The fish were relatively cheap so I bought all four hoping that there was both sexes in the tank.
Fast forward about 3 months and the fish, Oryzias celebensis, are starting to show some sexual differences. The males are certainly more colorful and not nearly as heavy bodied as the females. Both sexes show a very light blue sheen to the back of the body with the males showing a bit of yellow to outline the top and bottom. All fish have a set of black lines starting at the back of the body and going through the tail. As luck would have it (which is unusual for me), I ended up with 2 pairs in my 10 gallon tank. It is a bare tank with a sponge filter, some floating plastic plants and a floating spawning mop.
These fish sometimes called rice fish and other times medakas, come from Indonesia and according to the IUCN website (were listed in 1996) is red listed as a threatened species. The recent tsunami in Indonesia should not have impacted this fish in it’s normal waterways.
There are currently 3 different species of rice fish that are circulating through the hobby. The other two species are O. javanicus and O. latipes, all three are very similar looking and all reach 1.5 to 2 inches. The peculiar thing about these fish is that the female actually lays the eggs and they ball up in a mass in front of the anal fin. She carries them around until she disperses them in the mop, although I never found two eggs attached to each other in the mop.
These fish spawned readily when well fed on live baby brine shrimp, frozen adult brine shrimp and flake food. For those not familiar with the standard M.O. for killifish eggs, all one has to do is pick the eggs, with your fingers, out of the mop and put into a small container. It is important to keep the container away from light as light aids fungus. For most of my eggs, I will put some methylene blue as a fungal inhibitor. (A quick note is that when out of meth. blue I have actually used city tap water of same temperature as it is loaded with chlorine and has worked quite well. I have gotten numerous fry to prove it!)
Now I do not pull the mops everyday so I am not quite sure how long incubation takes but I am assuming at the temperature I keep them, low 70’s, it takes 7 - 10 days. I just check the container of eggs every other day and remove any fry to a small aquarium with no filtration and just some java moss. I feed the little guys Liquifry for about a week and start adding newly hatched baby brine as well. The nice thing about these fish are they are very peaceful and you can keep adding newly hatched fry to the tank forever. (Don’t try this with most killis or you will end up with only one!) Actually, I know people who just throw a ton of plants in a small tank and let the Oryzias breed and the fry grow up in the tank with the adults.
The fry have grown quickly and have become great dither fish for many of my dwarf cichlids. For a cichlid guy, I could not be happier with this fish! I do plan on maintaining them at this point, as I have gotten my BAP point for them but do like their peaceful nature. If you want an EASY introduction to killifish or just an easy breeding, peaceful fish you should give them a try! The end