Breeding Danio choprai Hora 1928
Author: Dr. Karel ZahrÁdka
The author details his experiences with breeding the beautiful and rare Danio choprai, and includes tips on how to care for the fry.
Danio Choprai History
The gorgeous Danio choprai was described in honor of Dr. Chopra by Hora in 1928, but it did not become popular in the hobby until the last few years. It comes from the Irrawaddy River drainage in northern Burma.
Danio choprai are small, attaining only about 3 cm (just over an inch). They are beautifully colored, with their color only looking its best when they are properly kept in schools. The school will be in constant movement, offering a beautiful display. Stressed fish, including recently shipped fish kept in bare tanks, are very poorly colored, so you might not be able to see the fish’s true beauty at a retailer.
In Czech pet shops Danio choprai and other new danios are very difficult to find, and you have to go to a wholesaler or breeder to get them. These fish are being bred commercially, but only for export. The local market offers only a few species, such as D. rerio. It’s a pity.
Danio Choprai Basics
The minimum number for a school of Danio choprai is 10 fish, with 20 being even better. In a well-planted tank of adequate size the fish will make a colorful, dynamic display. Under these conditions well-fed fish will usually spawn every 10 days or so, with all of the fish in the school spawning at once.
Flake food is greedily taken by these fish, but live food really brings out the color and increases the size of the spawns. A good regimen is to rotate among cyclops, daphnia, mosquito larvae, and a good flake food. I find it a good idea to add tubifex two days before spawning to maximize the number and viability of the eggs. The temperature should be around 22°C (72°F), and good filtration with adequate water circulation is necessary.
If you decide you would like to breed these fish, start by obtaining 20 juvenile fish; chances are that you will have about 10 males and 10 females, which are good numbers for schooling and fast conditioning. Make sure to feed them well, and within a couple of months the females should begin filling out with eggs. A 10-liter (2½-gallon) tank is fine for spawning these fish. I use a standard 30- x 20- x 20-cm (12- x 8- x 8-inch) aquarium.
The fish like to spawn near an object, so provide driftwood, rocks, plants, or a spawning mop. Even better is a spawning grate that confines the fish to the top couple inches of water, allowing the eggs to fall through to the bottom. Some years ago I had the opportunity to see Danio kerri spawn in a forest stream in Thailand. That tributary was only 10 cm (4 inches) deep and absolutely free of plants. The fish spawned between stones and also between my bare toes while I was standing in the water!
Providing a current is necessary—in still water the fish will rarely spawn. An airstone, powerhead, or return from a power filter will create the water motion. Good water conditions are pH 7, GH 2° to 8°, KH below 2°, and a temperature of 24°C (75°F).
Add five pairs (or seven males and five females) into the prepared spawning tank. Spawning should begin at about 11 a.m. and finish in the late afternoon. When your fish do spawn, several males will chase one female.
The actual spawning act is very quick. A female will produce about 50 relatively large eggs over the whole spawning. The eggs from the first spawning in the community tank are expendable, and a lot of eggs are not fertilized. D. choprai spawn in typical danio fashion, releasing a few eggs at a time. The non-adhesive eggs sink to the bottom, with the parents in hot pursuit to eat them. This is why a spawning grate will result in the largest yields.
When spawning is finished, remove the parents and the spawning grate. Within a few hours, unfertilized eggs will lose their original transparency and become cloudy. It is easier to identify them if you shine a light on them through the front glass. Illuminated from above, infertile eggs are difficult to detect.
For maximum yield the infertile eggs must be removed. I do this about four hours after spawning. After removing the infertile eggs, change half of the water and replace with water of the same quality and temperature. Early the next morning, repeat the procedure, removing all infertile eggs and changing 100 percent of the water.
Taking Care of the Fry
The fry hatch after 72 hours and begin to swim after 48 more hours. After they have all hatched, you must siphon all the shells from the bottom to prevent them from decomposing and leading to bacterial blooms.
Once the fry are free swimming, they must be fed. For the first few days they are too small for baby brine shrimp. You can feed infusoria, but they will also take one of the plankton-sized prepared foods. After three days they can usually handle newly hatched brine shrimp.
At about three weeks of age the fry get a red stripe on their sides. At this point many aquarists will mistake them for glowlight tetras! By two months of age, the fry have the normal adult coloration, and they mature at six months.
See the full article on TFH Digital http://www.tfhdigital.com/tfh/200710/#pg92