Nannostomus Marginatus

[seangee]

I mentioned in another thread that my stock of these is down to 3 in a community tank. These were purchased pre-covid so I am not too concerned about my ability to keep them .
I am reasonably sure I have 2 males and one female (but no guarantees )
I have now setup a breeding tank and I am almost ready to go.
My question is should I just move the 3 (or a pair ???) into the breeding tank or would it be better to buy a group of 10 and leave them in the breeding tank as a single species tank until they spawn?
I have read accounts that they are less likely to spawn if the group is too small.

What would you do?

 

[Innesfan]

The fewest or the most. I'd set up a pair or I'd go for a colony breeding. They are willing spawners. Among the most willing of the Nannostomus species. There are many populations which, I suspect, are about to be individuated as species. I've kept many and have never found one to be less willing to spawn than another. If you set up a pair, separate them for a while first.

 

[seangee]

The fewest or the most. I'd set up a pair or I'd go for a colony breeding. They are willing spawners. Among the most willing of the Nannostomus species. There are many populations which, I suspect, are about to be individuated as species. I've kept many and have never found one to be less willing to spawn than another. If you set up a pair, separate them for a while first.

Exactly what I was hoping to hear. Part of the reason for the exercise was to avoid spending money to replace fish , so I was planning to try with what I have first. I'll separate this weekend and start conditioning.
I have never intentionally bred fish before (although I did keep livebearers many years ago) so its re-assuring to start with something fairly easy.

 

[GaryE]

That's a fish that is almost impossible to find where I live. They were common for years, and then dropped off the radar completely. I have had an eye out for them for years, to no avail. Never take any fish for granted.

 

[seangee]

Seems to go in cycles here. At the moment they are readily available - although about 4x the price I paid for mine.

 

[Innesfan]

Exactly what I was hoping to hear. Part of the reason for the exercise was to avoid spending money to replace fish , so I was planning to try with what I have first. I'll separate this weekend and start conditioning.
I have never intentionally bred fish before (although I did keep livebearers many years ago) so its re-assuring to start with something fairly easy.

Lots of plants above and below and, if possible ph of 6 or below, though that's not an absolute necessity for this species. Ph-wise the species has a great natural range. There are several blackwater populations that thrive in Heckel Discus- sort of conditions with a ph in the 4s or below.

 

[seangee]

Lots of plants above and below and, if possible ph of 6 or below,

Slowly getting there. pH is no problem as I use RO. It's sitting at 5.5 with a little help from cattapa leaf, I'm frantically growing hygrophila and ambulia in pots as well as frogbit. I already have enough that I don't need to worry about cycling - even if I was to stock as a regular tank. But I will keep fertilising, lighting and growing for a couple of weeks. At the moment I am just leaving the cuttings to float free so it should be a mini jungle soon. I actually threw out enough cuttings from the other tanks today to completely fill this one - but not using these as I don't want to introduce snails. I have a very gentle trickle filter to ensure oxygenation.

 

[anewbie]

Are they a blackwater species ?

 

[Innesfan]

Are they a blackwater species ?

The Rio Negro and tributaries populations are. But there are dozens of populations in the massive South American range for the species that are not. And there are some pretty dramatic color variations among them. Probably why the splitters will be having a field day with them soon. I am told it is in the works.

 

[seangee]

Decided not to put it off any longer. I really wasn't looking forward to catching the little beggars, and my concern was justified. They are the smallest and most skittish fish in the well stocked and planted community. I managed to get there without dismantling the tank but abandoned my thoughts of separating the sexes and the 3 of them are now in here.

They are not the Rio Negro variety but I supplemented the catappa leaf with a couple of alder cones anyway.

 

[seangee]

Well the breeding tank is about to become a QT. The challenge of getting 3 males to spawn proved too great
I'll leave the 3 in there so for the time being this will be a temporary (famous last words ) species tank

 

[seangee]

Clearly I need to learn to use the gopro and how to edit when I am doing things other than pointing it at large objects while diving (or just stick to the phone ) .
The new arrivals are settling in. They look healthy enough and are a decent size.


Edit: Replaced video with one from my phone

 

[seangee]

One week in and all is well in their world. I even managed to count all 13 today.
Its a long time since I have bought fish but I am not sure I realised just how much stress shipping causes them. When I had 3 in the tank avoiding overfeeding was a challenge; but with no sand, no snails and no shrimps (not to mention new tank) was something I have been very conscious of. For the last week they have been eating but not with any great enthusiasm. Earlier today when I fed the usual amount they shot to the surface and it was gone in seconds. So I repeated tonight and got exactly the same result

The other thing I noticed was that I could distinguish the original 3 from the newcomers purely by colour, the old ones were brighter. Richer in colour is probably a more accurate word. Well suddenly I have a lot of these richer coloured fish. Not all though. I can't say for sure if the difference now is sexual dimorphism or just that some are completely over the stress and the rest are still getting there. (I hope the former because that makes things really easy ).

So its taken a full week. A few hours after installation I believed they were settling in nicely. I'm sure they were but full recovery took a lot longer - and may not yet be complete.

They appear to be of the same origin because they seem identical in appearance. Probably not surprising as they are all store bought and AFAIK most UK stock comes from Eastern European breeders. The retailer confirmed that was the case for the newbies. Here are some of them this evening

Edit: Oh and they have now started squabbling, which was not happening before

 

[seangee]

I mentioned before the little guys are almost motionless when asleep. This morning I did their water change shortly after switching on the room lights (dark tank) so they were all sleeping amongst the roots.
They never bothered to wake up while I was siphoning water out and it was quite surreal watching them serenely drifting down without apparently moving a muscle.
They did wake up when it started raining