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October 14, 2011

This week I would love to discuss with the world of Ricefishes from Asia…

There are now 29 known species of Ricefish. Out of these, 13 are endemic to the very small island of Sulawesi, which is located between Borneo and the Maluku Islands in Indonesia. Many of these species can be found living among rice paddies and that is where they get their common names. Their maximum sizes range from small as less than ¾” to as large as almost 8”. These fish have several interesting things about them, including an unusual bone jaw structure and even an extra bone in the tail! Most of these fish should be housed in tanks that are 10 gallons or larger. So let’s enter the world of the family Adrianichthyidae.

A global sensation swept across the hobby this year as a new species was introduced, Oryzias woworae “Daisy’s Ricefish”. They were found in a stream named Mata air Fotuno located in the Parigi district on Muna island of Sulawesi which is mostly covered by forest and that has a substrate that is a mixture of mud and sand. The woworae were found schooling with a new species of Nomorhamphus that were eventually imported under the trade name “Fire Halfbeak”. The pH was recorded between 6 and 7 and the fish will do well with these ranges in a home aquarium. Daisy’s Ricefish is a rather unfussy when it comes to food, but feeding foods that are either crushed or of small size and of high quality will bring out those bright red fins on their hourglass shaped body. Though it is not the smallest in the genus, as they reach a maximum size of just over an inch, it certainly is one of the most attractive. One thing that even I did not know about these remarkable fish (which goes for most of the genus and I shall discuss shortly) is that the fish attach their eggs to the outside of the female’s abdomen. I noticed this first hand one morning when we came in and were doing our daily observations. What a wonderful fish to be kept!

Oryzias woworae

Originally described from the mouth of the Hooghly River that lies south of Kolkata, West Bengal state, of eastern India comes the beautiful Oryzias dancena “Indian Feather Fin Ricefish”. Today research suggests that it may be found much more widely-distributed across South India, Sri Lanka, Bangladesh and Myanmar. The Indian Feather Fin Ricefish seems to inhabit coastal waters that tend to be strongly brackish, but also have been collected in freshwater forest streams and major river basins. Though they may tend to come from brackish waters, our batch has been collected from the freshwater regions and is easily adapted into a pH of 6.5-8.5. The Indian Feather Fin Ricefish is a micropredator that feeds on small insects and zooplankton in nature. In the aquarium small prepared foods such as frozen daphnia or chopped up frozen bloodworms will ensure prolonged life and the best colors these 1” fish will offer. The feather fin name comes from the long, filament-like extensions that the typically grow from the males’ anal fin. Just wait until a male is defending against another male in your tank!

Oryzias dancena

Though it has been described since 1986, Oryzias mekongensis “Mekong Red Fin Lampeye”, little information is available on these remarkably small fishes. Growing to just over a half an inch, the Mekong Red Fin Lampeye ricefish has a silver to white body and a bright red tail fin. As the common name suggests these fish are endemic the Mekong River basin in various tributaries of Thailand, Laos, and Cambodia. The only bit of research I could find was that in 1996 Rainboth said it occurred in ditches, ponds, and canals that are densely overgrown with fine-leaved aquatic plants. As the fish is extremely small it should be fed artemia or frozen daphnia. Feeding live baby brine shrimp might get these nano-fishes to breed more readily!

Oryzias mekongensis

If you are looking at breeding some of the Ricefish, it seems quite easy from what I have read. Females are capable of producing eggs every few days, or if they are in great condition, daily! Setting up a tank just for these fishes will ensure that the fry will be raised. Use sand or a fine substrate that is planted with small leafed plants such as Rotala, Cambomba, or Taxiphylum species – that will be the best breeding grounds for all three of the interesting fish listed above. You can even use little spawning mops if you have some available. Spawning normally occurs in the morning. The male will darken in color and begin fending off other males in attempts to court ripening females into the small spawning grounds of his choosing. Adhesive eggs are typically expelled in a single mass and fertilized by the chosen male, after which they continue to “clump” on the genital pore of the female before being deposited onto fine leaves of plants.

After the eggs have been placed the whole incubation period will take about 1-3 weeks depending on temperature. The adults will generally leave the eggs alone, however care should be given to the free swimming fry. It may be best to remove the parents from the aquarium. Feeding small micro foods like daphnia will help the quickly growing young to reach their adulthood!

This concludes The Wet Spot’s newsletter for the week. Perhaps you’ll set up a 10 gallon just to see the morning activities of some of these very cool fish that come from the East. As always be sure to check the products link for more exciting fish. Be sure to contact me with any questions or suggestions you may have. Thank you and see you next week!

Anthony Perry
Sales Manager