Rummy Nose Tetra Breeding

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Steve H.

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Location
Pingree Grove, Illinois
Hello all,

I am attempting to breed Rummy Nose Tetras. I have scoured the net researching only to find information is quite limited, and in a lot of cases articles contradict each other.
I am hoping that posting my project here I will attract some discussion and insight from more experienced breeders/aquarists to help me along.

Since there was a lot of differing information out there I took bits and pieces of what I had read, and put together my own little breeding project.

Stock:

My first step was to acquire breeding stock that would produce viable eggs. In my research I had read that RNTs that were kept at a pH higher than 6.5 for a duration of time could leave them sterile, and unable to produce a viable spawn. Not wanting to be shut down before I got started, whether this is true or not, and to be on the safe side I acquired 11 wild caught RNTs. My thinking was that if they were kept at a higher pH than 6.5 it was at least not for very long.
I homed them in an aquarium of 6.2pH and 2gH for several months before making this attempt to breed.
My tap water parameters are quite hard, so in order to maintain these parameters I use a combination of RO/DI water, almond leaves, bog wood, and sphagnum peat moss.

Breeding Aquarium:

I decided to try using a 2.5gl aquarium for breeding a male/female pair.
Since this is a tiny tank I was able to build a screen to cover the entire bottom of the tank using #5 plastic cross-stitch meche, and some plastic tubing.
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It fits snugly into the tank and will let the eggs fall to the bottom while keeping the parents from eating them.
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To condition the breeding tank, and age the water, I added long strand sphagnum moss under the screen. This is to not only help maintain water parameters, but provide a place for the eggs and first foods if I am able to produce fry.
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While the breeding tank aged I did my best to condition the breeding stock...now only 8.
I divided a 10gallon tank with a similar DIY screen, and did my best to separate the males and the females.
This is no easy task, and I'm still not sure which is which. They say the female has a rounder body shape...uh ok. They still looked all the same to me. I must have switched them around a dozen times finally just settling on size and shape being the closest to each other.
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For 2 weeks I feed a lot of different foods. Mostly frozen daphnia, but also black worm flake, and live brine shrimp.

After conditioning I transferred the entire stock to the breeding tank...this is because I could not be sure of which were male and which were female.
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In order to try triggering a spawn I drained the breeding tank by 70% and refilled using slightly cooler water. Then drained again to a 4" depth of water.

I then covered the tank with some towels as the eggs and fry are said to be photo sensitive.
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There I left the adults for 42 hours....and that's where I am in the project right now.

I just removed the parents and the screen from the breeding tank, and covered the tank back up with a towel.

While removing the adults I noticed they were very pale in coloration...this is a good sign that spawning might have occurred.

Now, I guess it's time to cross my fingers and check in 4 days to see if I was able to produce anything.

The only thing I didn't do which I planned on was adding some meth blue, but didn't because of the peat moss in the tank.

I would love to hear some success stories if they are out there.

Pointer, tips, or advice as well!!

Thanks for reading



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Last edited:
Cool project Steve! I have no experience with breeding but I love rummynose tetras, definitely one of my favourite fish. Looking forward to hearing and seeing your progress!
 
Cool project Steve! I have no experience with breeding but I love rummynose tetras, definitely one of my favourite fish. Looking forward to hearing and seeing your progress!

Thanks!! Best schooling fish in the trade imo. I hope to have some good news in a couple of days.

I've had a lot of success breeding Angels and Apistogramma, but these guys and Cardinals are a bit tricky and more challenging. Maybe that's why I could not find too many breeding success stories out there on the net.

I also have a group of Cardinals to breed if this method is successful.
 
Swing and a miss.

Nothing on this attempt.

I am altering my method on this next attempt. This time I am not going to use the sphagnum moss. It's just too messy. If I even did get eggs or fry there's very little chance I would be able to locate them in all that.

To achieve the neccessary pH and GH I'm going to use Indian almond leaves and diy black water extract.
Now, try as I might I can not get my pH below 6.2. ro/di water, Indian almond leaves, peat moss....nothing natural is getting it down to a 5.5 - 6.0 where I would like to be.

I will also be adding a small spawning mop to see if that does anything.


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The biggest challenge has been determining the sex of the fish.
I have looked everywhere for information in how to determine this. The only thing I could find was body shape. Females are said to be rounder bodied when they are carrying eggs. I even found in one article to look down upon the fish from above, and see if the sides bulge. I thought this was my sure thing....uhhh no. They still look all the same to me.

I figure now the only way to determine the sex is too condition them well then try and trigger a spawn that won't produce any fry. Just have to see who is chasing who, and hope to separate them that way.
 
Nice Steve. Only thing I am asking myself if they don't spawn in a bigger school (not a.pair).


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Nice Steve. Only thing I am asking myself if they don't spawn in a bigger school (not a.pair).


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I agree. I have read they will spawn in groups or a single pair. However, in a group it's necessary to have a favorable ratio of males to females.

But, that's where info starts to contradict again. However, most seem to agree that a 2:1 or a 3:2 males to females works.


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I have been feeding well and a big variety in hopes of plumping the females up.
I started to try and separate the males and females today, and I think I may have discovered something that will help determining the sex of my rummy's. Males have a small hook in their anal fins. As I separated them 1 by 1 I noted those who got stuck in the net, and after a visual once over determined they were male.

Not sure if this is perfect, but it's the closest I have gotten. I now have 3 females separated from 5 males, and I will condition them for the next week before a second breeding attempt.


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Hey Steve, great project!

Check youtube on spawning RNT, you might get a better idea of the sex differences.

Did you ever observe spawning in your big tank? If not, imho there is no need in trying in a separate tank. I think you can also condition the group together and as soon as you observe the first spawning, you would transfer some fish to your breeding tank.

Normally you would not age the water in the small tank but use water from your big tank to fill it.

Did you keep your breeding tank covered (i.e. dark) the whole time while you had the fish in there? Then your fish have been sleeping more or less the whole time. For this reason you also see the pale color. They will breed during daylight, meaning they need a normal day/night cycle.

Good luck!
 

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