Breeding Neon Tetra

[S_Hurley]

Can anybody post a picture of a male and female Neon Tetra and tell me how to clearly sex them?

[genocidex]

directly from this site:
"Sexing Neon Tetras can be hard, but the female usually have a bigger and rounder belly than the male. The blue line will be straighter in males, while the round female body creates the impression of a bent blue line. When she is ready to breed, her body will become very broad since she is filled with eggs. " best i can do for you....

[Trillianne]

Mine have never bred, and from what I understand the eggs are photo sensitive (light sensitive) so its definitely something you want to research more so you set things up correctly.

These aren't the greatest pictures but...

In the foreground the one on the left that is swimming away from the camera is one I'm fairly certain is a female. Ones the right and in better focus is the male. Notice how flat their stomach area is compared to hers. (And I assure you, she's nearly always more round like that, its not an overfed fish)
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A slightly better picture of the female:

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[Lady Hobbs]

The reason these fish are still imported is due to the difficulity in breeding them. Same with cardinals. Tetra's are easy breeders other than these fish.
There are only bred in a few fish farms outside of the US but most are taken from the wild.

[korith]

Trillianne hit it right on the nose, the eggs are sensitive to light. People that do mass breed them do it dark tanks and avoid exposing them to light.

[dbosman]

I stole/borrowed this off a website, that I forgot to add the citation for.
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I decided to set up a new tank; this time 75cm/30” long, again with rainwater, and with a 2.5cm/1” deep layer of freshly collected oak leaves and one bush of Java moss. I introduced two pairs of adult Neons and watched for about 14 days.

Two things happened. First the water began to go brown and more acidic as the oak leaves softened, and the DH became less than 1, pH less than 5, temperature was 26°C/78°F. The fish took about a week to feel at home in the new tank, but then began to spawn every morning as the room lights were switched on.

The water, tannin stained, became darker and darker and I removed the adults at 14 days and waited. After about a week later I peered into the darkness and spotted a single fry moving hesitantly through the leaf litter. In subsequent days I spotted more and more and I added newly hatched brineshrimp, which they relished.

After about a month I was counting more than 30 fry, and in total this attempt produced about 100 young.

I’m not sure that the pH is critical, but the darkness is. The eggs and fry are susceptible to light, but I believe that the brown water and leaf litter also hid the eggs from the hungry adults which I had fed only sparingly in the breeding tank.

Encouraged by my success I decided to use a similar but larger set-up to try and spawn Congo tetras, but within 24 hours of placing them into the acidic conditions the adults had died.

The Neon tank had acidified over several days and the fish had acclimatised during that period.

However, with the Congos I foolishly let the tank ‘mature’ for a couple of weeks and the fish succumbed when placed into conditions very different to their natural home.

Young Neons colour up at about four weeks and under good conditions are large enough to sell at 12 weeks, but your dealer won’t thank you unless you gradually change the water back to tapwater. I did so over about four weeks and had no ill effects.

Do some babies grow faster?
One breeding observation still puzzles me. Up to eight weeks after I first spotted fry in the breeding tank, tiny colourless babies still continued to appear. Yet the first baby Neons were already large enough to go back to their parents’ tank and become part of the crowd.

I don’t think it possible that the ‘older’ babies were already breeding as this had been a continuous process, a few tiny babies appearing each day or so. The only reasonable explanations are that some grow much faster than others, or that some eggs experience delayed hatching — as do many killifish.

The former theory is most likely, as the latter would surely have been noted earlier by better observers.

I’m speculating that in nature some baby Neons stay small and undeveloped, hiding in leaf litter so that if their body of water becomes cut off and evaporates, killing their faster growing siblings, they can survive in tiny amounts of water until the rains come.

I have noticed similar situations with Apistogramma and Ctenopoma, and can’t think of any other explanation.

[dbosman]

I Google's a phrase in the post and found the original site.

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Breeding expert John Robertson describes how he raised Neons – one of the world’s most popular and recognisable tropical fish.

[Lady Hobbs]

Another thread now moved.