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Re: N. rachovii KNP

Ryan Reisinger wrote:

> 
> George Morris wrote:
> 
> > Good morning everyone.  Why is N.rachovii KNP Black so rare?  I understand
> > that it has a pretty long incubation time, that's not a problem as far as
> I
> > am concerned, are there other problems breeders have?  I've never seen it,
> > is it really black?
> 
> There are a number of reasons for the rarity of N rachovii KNP Black.  This
> fish is from a  small locality within the Kruger National Park, South
> Africa.  All true KNP Black originate from a single introduction into the
> hobby by John Vermaak in 1984.  Also, this species is on the Red Book List
> for RSA and it is therefore illegal to collect them without a permit.  There
> is almost no chance of being granted a permit by South African National
> Parks to do so.  Another important matter is that KNP Black specimens have
> not been recorded in the park for a number of years, possibly due to the
> prolonged droughts or damage to the habitat during one year.
> 

I think that George was referring to the rarity of this 
population in the hobby. As you say, this species is known from a 
single location only in the KNP but, in actual fact, the "black" form 
of N. rachovii is very common in southern Mozambique (there are 
about 5 MOZ 99 populations of N. rachovii Black in the hobby at 
present, but who knows how long they will survive). The probable 
reasons for rarity of the KNP population in the hobby have nothing to 
do with its status in the wild. What are those reasons ? I would 
speculate as follows:

1. While this Notho can be very striking when kept under conditions to 
its liking, it can also look very plain when not 100 percent happy. We 
all know what the fate of unattractive Nothos in the hobby is, 
apparently, in spite of their "rarity". This is only one of a number of
uncommon or rare Nothos that have disappeared from the hobby for a 
similar reason.

2. It has been my observation that, in general, Nothos that tend to 
have very long incubation times are also those that are either very 
uncommon (in the hobby) or disappear from the hobby very quickly. Apart 
from N. rachovii KNP, consider for example, N. orthonotus, N. kuhntae 
and N. furzeri. All of these have always been rare in the hobby and all
have relatively long incubation times. Since 1984 there have been 13 
populations of N. orthonotus and N. kuhntae introduced into the 
hobby (5 in 1999 alone). How many are still being maintained ? The 
aquarium strain of N. rachovii seems to be an exception to this general
rule, but then it has been very long established in the hobby.

The obvious question that arises is why long incubation times should 
lessen the chances of survival of a species in the hobby. I think 
there are a number of factors: 
(a) With long incubation times there is a greater chance of the eggs 
dying in the peat usually, I would suspect, because the bags get 
forgotten about and the peat dries out excessively. Plastic bags do 
breathe and allow the peat to dry out. Maintaining the correct moisture 
content in a bag of peat for what may be a year or more requires some 
attention from time to time and is not always the simple operation that
it might seem to be. Storing the peat in a completely sealed container
is also not the solution to this problem as the eggs require oxygen and
the container must be able to breathe somewhat.
(b) Most hobbyists simply do not have the patience to wait out the 
necessary long incubation time and either give up or start "messing 
about" with the eggs, e.g. wetting and redrying them too frequently, 
storing them at excessively high temperatures, water incubation, force 
hatching, etc.
(c) With long incubation times one generally also gets erratic hatch 
rates because the eggs develop at such wide-ranging rates. Quite often 
the result of this will be small batches of fry and consequent small 
numbers of breeding stock. If sex ratios are badly skewed the problem 
is made even worse. These species also tend to be very short-lived so 
keeping a batch of specimens of one sex for 2-3 months until one can 
hatch out and raise another lot to a compatible size is generally not
practical.
(d) Some of those Nothos with long incubation times also tend to be 
very aggressive so getting a decent amount of eggs from them before 
the females are killed off can be difficult. Obviously, N. rachovii 
does not have this problem.

Maintaining certain Nothos in the hobby, especially those with long 
incubation times as discussed above, requires patience and commitment. 
A degree of experience with other, easier, species is also an advantage.
__________________________________________________
Brian R. Watters
Professor and Head
Department of Geology
University of Regina
Regina, Sask. S4S 0A2, Canada
Tel: (306) 585-4663
Fax: (306) 585-5433
E-mail: Brian.Watters at uregina_ca

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