Oryzias latipes or Japanese Rice Fish can be found in east Asia – Japan, China, and South Korea. They are a peaceful fish, suitable for a well planted community aquarium, if the tank mates are not large.
As a rule the males are more slender and their anal fin is larger and ends more pointed. The colouration is more intense. They will grow to a size of about 2 1/4″ (5.5cm).
They like medium to hard water (10-15 degrees dGH) pH of 7.0 and a temperature of 64 -75 degrees F (18-24 degrees C). They like aeration and water movement. The water should be clean.
Purchasing the Japanese Rice Fish
I knew very little about rice fish when I purchased a trio of two females and one male. They were placed into a small three gallon tank with the temperature and water requirements as mentioned. I placed in the breeding tank a sponge fry filter and a wool mop. At the same time I also set up a tank for hatching the eggs.
Breeding
I gave the fish a few days to become accustomed to their new home; then every 2-3 days I removed the wool mop and squeezed it out. Sure enough, I always found 4-8-10 eggs clear as glass. I picked them out, attached them to a small piece of Java moss and placed it in the rearing tank. After a week or so I had over 80 eggs. The eggs hatched in 10-12 days. I kept a record of how many eggs I transferred and the dates. After 10 days I found one small fry, them 3 and finally 5. I wondered why only 5 hatched out of 80 eggs.
Because I like to experiment, I set up another three gallon tank with RO water – pH 7.0, a fry filter, and kept the temperature around 80 degrees. I again gathered eggs for another week and retrieved another 80. After 10 days I began seeing fry, and after a couple of days I counted over 30 fry. Now I was satisfied.
Carrying eggs on anal fin
Now during this time, as mentioned, I knew very little about these fish. I noticed one female had a string of eggs stuck to her bottom anal fin. I was shocked and wondered if this was normal, or maybe she had a problem and couldn’t get the sticky eggs off. So on two occasions I caught her in a small net and gently removed the eggs. On placing her back into the tank, she appeared to be unconcerned with what I had done. The eggs I placed into the rearing tank.
Then luckily I received a new reference book. I learned that the female may continue to carry the eggs in a bundle in front of the anal fin. The eggs are linked together in a grape-like cluster and will be brushed off on plants, etc. Now I knew it was perfectly normal for the eggs to be attached to the female. Problem solved – I was only trying to help.
The fry have survived and grown and have been easy to raise. With each water change I have added hard water and they are still content and growing. They have been fed dry sifted fry food and later live brine shrimp.
I was pleased to have the chance to breed these fish because we learn something new each time. Now with a little more knowledge and experience we can carry on and try something new again.
First Publication: Fins and Friends, Regina Aquarium Society, Canada.
