Sexing Denision Barbs are among those species that are notoriously difficult to sex. However, this archived forum discussion gives a few tips about sexing and breeding them.  Visit the forum for the latest fish and aquarium chat.
From: guitarjeff  To: All
I have a question regarding the dimorphism of denison barbs. I purchased one last night that was larger than I'm normally able to get (~4") It had paler coloring too which made me think it was a female.


Considering possibly breeding these, I thought it was a great find. Could be the reason they supposedly don't breed in captivity, because they're only distributing males. Just a guess. Either that, or it's pale because of some illness. It doesn't behave abnormally and was looking for food as soon as it got in the tank. There's isn't much info on the web for these, so any help from the forum would be greatly appreciated.
 
From: thatmagicguy  To: guitarjeff
I don't know of anyone personally breeding them, I wanted to get some a ways back to try my hand at breeding. I was going to get some off aquabid. The guy sent me a photo of the group he was selling, I saw no discernable differences in them so I did not buy them, considering the price. I have looked at pictures on the net and some have considerabley more red on them, some have less and some do seem to show the broader abdomen that you would expect of a female. I cannot think of too many barbs that the male and female are completely different colored, the closest would be the ruby barb and cherry barb, but these are seasonal male colorations in the wild.

Of course there are many man made versions where the male exhibits spectacular color differences. But these fish are supposedly wild. All male barbs tend to show more color, but not to the extent of dimorphism.

If I was going to breed them I would try in the traditional way. I would separate a "male" and a "female" for about two weeks, during which time I would feed primarily frozen and live foods. This particular species supposedly gets 6 inches so I would not try anything under 3 inches for breeding.

I would set up a 20 gallon long tank, I would use nylon mesh to drape inside to let the eggs fall through, they will no doubt be semi adhesive.I would put the female in the tank around 5 pm and just at dark I would put the male in. I would then be present at dawn to see what happens.If these fish are wild caught then they may be subject to seasonal stimulation. This can be beaten by keeping the male/female separate in warmer tanks, flake foods, lower amounts of water changes for 2-3 months.Then you can start increasing the water changes to once a day, lower the temp a bit and beef up the feedings with lots of live food, then culminate the procedure by doing the 20 gallon long tank thingy.

The other option would be to just keep the group in a large tank, feed well, and put mops in to recieve the eggs, similarly to rainbow fish and then pull and replace mops periodically to check for eggs. Barb eggs are not as durable as rainbows and killies and cannot be handled the same way. So the mops would not be examined by hand for eggs, just moved to a hatching tank.

I would assume that the eggs hatch in 2 days or so, depending on temperature, and the fry no doubt go free swimming 5 days or so beyond that. If they are like most fish in these groups they no doubt have very tiny fry.Anyway, I sure would like to have a go at them.

Bill
 
9/12/08   From: 1077  To: guitarjeff
Jeff, when you say the new fish began searching for food as soon as it was put in the tank , I hope you meant quarantine tank considering that you described it as looking somewhat pale. While it is true that some males or females depending on species are more colorful than the opposite sex, You must not rule out the possibilty of a sick fish.
 
9/12/08   From: guitarjeff  To: 1077
Unfortuantely no...I put it in my 20G community tank. I don't have a quarantine tank or a breeder tank yet, but plan to along with my 75G set up. I usally observe the fish itself and the other tank occupants at the LFS before I buy. I did some homework, and there's a close species to this that often get sold instead. It's a Puntius Chalakkudiensis rather than the Puntius Denisonii. This variety tends to have a more robust body and is paler in color. My guess is that one of them got into the mix at the LFS. I'm not sure if that's what I have, but it's a strong possibility.

I'm still hoping it's a female so I can try my hand at breeding them. Bill gave me some great info on the process and I will follow it to the letter. Who knows...if I'm succesful, I'll send Bill a couple as a reward for his information. If they can last from India to the USA, I'm sure they'll make the CT to FLA trip. ;~)