Sexual maturity age for harlequin Rasboras?

yhbae

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How long does it take for them to become sexually mature?

I am trying to setup a breeding tank and I think I know what I am supposed to do to get them to spawn. The only question left is, whether my rasboras in my community tank are mature enough. How can you tell, in general, a fish is ready to spawn? My female one always looks fatter than the male one.

The largest one is probably around 1.5 inches (may be a tad larger) - it has grown up significantly during the past 2 months or so.

Has anyone experienced breeding Harlequins?
 

Lateral Line

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I've bred R. heteromorpha. From your description, I would suggest your fish are old enough. I don't know a hard and fast rule - much seems to depend on the conditions they are kept in. I'd say go for it with what you've got. I don't recall mine being particulaly large, they had been in my tanks for probably the best part of a year before I got around to them.

I guess you've already done your reasearch - but try to watch the spawning. The way the male wraps around the female is very different from the haphazard egg scatterers - interesting to watch.
 
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yhbae

yhbae

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Lateral Line said:
I've bred R. heteromorpha. From your description, I would suggest your fish are old enough. I don't know a hard and fast rule - much seems to depend on the conditions they are kept in. I'd say go for it with what you've got. I don't recall mine being particulaly large, they had been in my tanks for probably the best part of a year before I got around to them.

I guess you've already done your reasearch - but try to watch the spawning. The way the male wraps around the female is very different from the haphazard egg scatterers - interesting to watch.
The colors of two of them are especially intense (one male and one female, both are two of the largest). I'd say they've been getting good food which includes the usual flakes, freeze dried tubefix worms, freeze dried blood worms, hatched brine shimps, freeze dried brine shrimps, shrimp pallettes and freeze dried daphnia. I circulate them weekly...

I have read every article I could get my hands on about breeding them from google.com, so I guess I know the theory with zero experience... :D I have yet to see any spawning activity although I do have some wide-leaved plants in the community tank.

My pH is at 7.2 and usually goes up to 7.4 when it gets aerated well... I purchased some peat moss so that I can bring down the pH to around 6.

I'd appreciate if you could address some of these questions:

1. Do I need to put the pair in the breeding tank at 7.4 then gradually bring down pH by adding some peat in the filter? (I can't think of any other way to do this without stressing them out).

2. Does plastic plants work ok? I bought some silk Cryptocorine (sp?) just for this purpose since I currently don't have any wide-leaved living plants (I do have java ferns, but I don't think it would work due to their size...). Do you know if they spawn on these artificial plants?

3. Some suggests to lower the water level once spawned. Did you have to do this as well?

4. What did you feed once their egg sac is used up? Can they eat baby brine shrimps right away or do they need to start off with infusoria? (I know how to hatch BBS but I have yet to try to culture infusoria, yet). I get conflicting stories on this one - some says they cannot take BBS from the begining, while others say you can...

Appreciate any help!
 

Lateral Line

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Firstly, I always keep my breeding stock sexually segregated, males in one tank, females in another, and condition them seperately. I find that the females become better conditioned that way, if there are males around, they tend to be harassed a little and often drop a few eggs from time to time. Keeping them quiet gives a very full, very receptive female.

Secondly, I'd add some frozen bloodworm to their diet. Freeze dried stuff is okay, but frozen is better. If you have a source of safe live food, I'd be giving that as well.

A well conditioned pair will frequently begin to spawn within a few hours of being introduced to a breeding tank if they have been kept apart. If not, then you need to trick them!

Most, (all that I have dealt with - probably all generally), of the small Rasbora a seasonal breeders. They begin breeding at the onset of the rainy season, (in the wild of course). So what you need to do is consider what this means. Large quantites of pretty much distilled water suddenly start falling on the habitat. Obvious effects are, dilution of mineral/pollutant content, drop in temperature, and flooding to a shallow depth, areas which were previously exposed. Perhaps now you can see the logic behind stories of reducing pH, temperature and water level!

Once you've got them to spawn, take them out as they'll hunt down and eat the eggs. Water conditions are very important - the fish may well spawn, but the eggs won't hatch if the water is anything other than soft. The Ca++ ions react with the egg shell and make it impossibly for the fry to break out.

Specifics...

1) I think I've covered that already to a certain extent. My stock fish are held at pH 6.5 - 7.0 and breeding tank somewhere between 6.2 and 6.7, i.e. slightly lower. That change does not stress the fish, it is part of the stimuli.

2) No idea - always used real ones - sorry. Can't see why not - but then, I'm not a Rasbora.

3) Again - covered to a certain extent. The fish move into water areas that are flooded to a shallow depth because the larger predatory fish cannot follow them. My breeding tank is usually only 150mm - 200mm deep. I don't drop it further, but can see valid reasons for doing so, just don't go mad.

4) R. heteromorpha eggs are small, because the fish is small, but actually larger than many egg scatterers that lay 1000's of minute eggs. The reason you get conflicting stories is because we are not dealing with machines. In every batch of fry there will be larger ones and smaller ones. In every batch of brine shrimp nauplii there will be bigger ones and smaller ones. With a small fry species, even the big ones can't eat the smallest nauplii, so infusoria is required. In a borderline case like this, there will be enough larger fry and smaller nauplii to get some results. You will always get better results if you feed basically small fry with a mixture. Of course, if, (as I stongly recommend), you have two very well matured sponge filters in the breeding tank, their surface becomes covered with phytoplankton/rotifers etc., and you'll see the fry congregate around the sponges for that reason.

I could go on - but this is already turning into a book!
 
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yhbae

yhbae

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Thank you for the feedback!

For separation of the pair, I have a 10g and I have a tank divider for that tank as well. Could this work? :D Otherwise, I suppose I can move the female first into the 10g tank, then the male a week later... (I hope that doesn't stress out the female since they are supposed to be schoaling fishes after all).

I'll need to work more on the live food - I only know how to hatch BBS and nothing else... (Well, infusoria sounds simple enough, but haven't tried yet, and probably useless for conditioning a breeding pair). I think my LFS sells some frozen food so I'll check that out!

My tap water is pretty soft, at 2KH. I was planning to pre-treat the water with some peat to bring down the pH/KH further to the level you have recomended. I hope this will be sufficient.

I was going to use a big ball of java moss for providing microscopic food (I deliberately grew a huge ball of java moss for use in the future breeding tanks - it occupies about 1/2 of my 10g tank in volume...). But your mature sponge idea sounds great! Perhaps I'll do combine both... :D
 

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