Nannostomus mortenthaleri problems

**Gert** · 3rd Aug 2010, 00:17

Hi everybody,

Maybe the people around here can help me with the next problem I've got.
For 5 a 6 moths I've kept 15 Nannostomus mortenthaleri and just from the beginning of last week I've lost almost the whole group, and got now 4 left (1f and 3m). I keep them in a approx 200 litre tank (120x45x55cm).
p1100607q.jpg
Other tank mates are:
17 Nannobrycon eques
5 Microgeophagus altispinosa (Will be leaving the tank)
4 Otocinclus sp.
2 Apistogramma borellii (my own breeding and will be leaving this tank)
1 Apistogrammoides pucallpaensis male (searching for one or two females)

The last few weeks I was busy with lowering the conductivity of the water, by using RO water. The Water Parameters are of the tank are now:
PH:6,5
GH:3
KH:2
NO2:0
NO3:10
PO4: not readable
Temp: 27 degrees Celsius
EC: 294 µS

What am I doing wrong because I can't seem the cause of the death of almost the whole group?

**Gert** · 3rd Aug 2010, 17:29

If read somewhere on the internet that the Nannostomus mortenthaleri doesn't do well in a tank with Nitrate (NO3) in it. Is this true or is this a false fact? My Nitrate (NO3) value is : 10.

**tetroid** · 8th Aug 2010, 10:38

I haven't found n. mortenthaleri to be particularly sensitive. In hardiness, they are similar to other characins. A sudden die-off of any fish can be due to a lot of reasons - ammonia spike, contaminant in the water, rapid change in water parameters, or the introduction of a pathogen are all possible.

If ONLY your n. mortenthaleri died off, well, that would indeed be odd. If that's what happened, I would consider the possibility that they had a manageable health problem when you bought them (like an internal parasite load), and circumstances changed just enough after several months to give the illness the upper hand. That's pure speculation, though. Usually in a situation like that, you'd lose fish one by one over a long period of time, rather than all at once.

To avoid such situations, I always treat wild caught fish with a full course of metronidazole in their food and praziquantel in their water. Even if they don't show symptoms, they're always carrying something.

**Gert** · 8th Aug 2010, 14:59

Thanks for your reply. I've been talking with someone of the LFS who also sale the Nannostomus mortenthaleri and came up with the same thing. He also thought that the mortenthaleri's had an internal infection or parasite. I've the next one will die, he told me to bring the dead fish so that he can have a look under a microscope to see if the fish had a internal parasite. He also told me to treat the new introduced fish with a anti-biotics. Tomorrow I am going to get five new mortenthaleri's to have a new try and see what they would do.

**tetroid** · 9th Aug 2010, 10:14

If you do find out what was killing your n. mortenthaleri, please post. Some time ago, I had a problem with mine dying off one by one over a couple of months, along with some of their n. trifasciatus tankmates (who are very similar). No other fish were affected, and I had only had the n. mortenthaleri for about three months when it started. The symptoms varied - some bloated, while others wasted away. At one point I thought it was neon tetra disease, and at another point I thought it was fish tuberculosis. In retrospect, I think the primary cause was internal parasites, with infection as a secondary symptom.

As described above, I finally treated the whole tank with praziquantel while feeding all the fish exclusively with frozen food that I'd soaked in Seachem's metronidazole and an antibiotic binding agent called Focus. I fed them the mix for three weeks. There was one more death during the treatment, and then that was it. No deaths in almost a year now.

Good luck with yours. It's always sad to lose these beautiful (and expensive!) fish.

**Gert** · 9th Aug 2010, 16:50

If I have found the cause of what is killing my N. mortenthaleri is will post it here. Yesterday I had contact with Tom Christoffersen of http://apisto.sites.no/default.aspx and he'd said to me that if I can't find any visible cause for the death of the mortenthaleri, then it is mostly a bacteria or virus that they are caring and will develop in water that has not a really low PH value. I'm going to continue to lower my PH and EC value and see what that is going to do. I also will buy antibiotics to treat then and see what that is going to do.

**Zenislev** · 30th Oct 2010, 18:00

Most likely cause of bacteria. However they really need low PH to thrive well, i had quite afew bad experiences too....one by one they will just die off. Sometimes they develop dropsy too.

**tetroid** · 5th Nov 2010, 11:33

Could be bacterial, but I'm kind of leaning toward sporozoan again. After a long period of no deaths or illnesses, I lost another five fish over the past couple of months (4 n. mortenthaleri and one n. trifasciatus). My n. marginatus and n. eques were unaffected. The only thing that changed is that my UV filter bulb burned out.

The disease looked like dropsy in three of them, but in two of them the disease manifested as a twisted spine with white flesh on the back and little white cysts protruding. Reminded me of neon tetra disease. A full course of kanamycin had no effect. Whatever it is, it does most of its damage internally, isn't highly infectious, and kills very slowly.

At any rate, all the remaining fish appear to be healthy, and I've gone completely blackwater now. No KH, with a PH of 5 and GH of a little over 2 degrees. I just need to get my UV filter working again. Hope that's the end of it. I've only got two coral reds left.

**Zenislev** · 13th Nov 2010, 22:27

Black water should help to a certain extend, do update us more...

**Gert** · 14th Nov 2010, 07:25

From the group I have now I lost one large male, the other 12 specimens seem to haven no problems and look healthy. The one I lost had black dots on his body but it was no swelling. He was also bullied by the other large males. I'll keep an eye on the other 12 I've still got.

**Gert** · 7th Dec 2010, 20:56

I've got also problems again with my group of N. mortenthaleri. The fishes that I lost a shown some similar symptoms. They can't swing normal any more and the tail is hanging lower than normal. They are breathing faster and they also shown white flesh on there backs. It started with one specie that I directly removed but now I lost 3 other species and another one is showing this symptoms. The water conditions are:

PH:6
GH:1
KH:0 or 1
NO2:0
EC:100µS
Temp:26°C

What could be the problem and what is the best thing to do?

**tetroid** · 16th Dec 2010, 11:24

Sorry to hear about your fish. This thing is very frustrating. I suggest you check out this article by Diana Walstad: http://www.atlasbooks.com/marktplc/00388mycoarticle.pdf

I stumbled across it recently, and was quite surprised at how similar the disease she described was to the disease that has been killing my (and possibly your) n. mortenthaleri. The only treatment is to remove diseased fish quickly and use a UV filter. As I mentioned up the thread, the disease returned to my tank some time after my UV filter burned out. It's worth a try.

I bought three more n. mortenthaleri. The two survivors from the last batch are doing fine. It's hard to resist this fish! Good luck with yours.

**apistomaster** · 4th Apr 2011, 06:45

These Pencilfish are harder to keep than most. very soft, acid water is important but they have a higher degree of intra-specific fighting than most pencilfish.
Use twice as large a tank as you would think they should need because they need a lot of personal space and hiding places among fine leaved plants.
I have kept most of the pencilfish species and I still have not been satisfied with my degree of success. In fact, I have been surprised how challenging they are to keep long term.
They are so expensive it is hard to afford to keep trying them until you have their husbandry perfected.
I am sure I will try them a 3rd time but I will allow more space and feed more small live foods. Not a beginner's species.