Re: [Killietalk] Temperature and the number of vertebrae (before: Diapterons: defect genetic or enviroment )

[Miguel Angel <misaher at yahoo_es>]

Thanks everyone for your responses. They was very interesting for me.

Summary: I breed the diapteron at the temp of the my fishroom. At winter is around 18-21ºC (64-70ºF). I incubate the eggs at the same temp and I don?t use incubator. The TDS of the water that I use is around 400ms. They spawn well at these conditions.
A friend had a very hard troubles with them and he has a fish ?humpbacked?. I t could be cause the low temp and the lacking of vitamins as you have tell us. 

If they have more or less vertebrae don't matter. Maybe they have more vertebrae but more little. ¿?. Certainly looking for meristic data I don't find any from the osteology. Maybe it is very variable.

I want to make an experiment when winter comes. If  I get enoughs eggs from them I try to incubation  with and without incubator with different eggs and development of some fry in aquarium with heater and other without it. The problem is to get enough eggs for the experiment. I need enough fry for four aquariums.
 
Another question is the temp of maintenance of diapterons. All the people say that the diapterons are from cool water. I keep in summer at 24-26ºC and they are very well. Certainly they spawn better at 22ºC (71ºF). I think they don?t demand always so cool temps like 18ºC (64ºF). I have more troubles with the temp of sjoestedti than diapteron. At 27-28ºC the sjoestedti fall illness and die if I can?t fall down the temp.

Thanks everyone from Spain.
Miguel Angel Saiz




Date: Mon, 06 Aug 2007 10:22:36 -0700
From: Barry Cooper <bjc3 at centurytel_net>
Subject: [Killietalk] Temperature and the number of vertebrae
To: killifish discussion list <killietalk at aka_org>

Recently we had a discussion on the potential effect of temperature on 
the number of vertebrae in fish, in the context of whether temperature 
effects could account for the marked shortening of the body length that 
a few of us have seen in offspring. I indicated that I had found a paper 
on this topic in Nature (May 16th, 1959). I have now obtained that paper 
(actually a very short letter) and below summarize the results published:

1. The literature cited indicates that the belief at the time was that 
lower temperatures actually INCREASE the number of vertebrae. These 
studies included the killifish Fundulus heteroclitus.
2. Another cited study done in Salmo trutta trutta had found that the 
lowest average number of vertebrae occurred at an intermediate 
temperature, with both higher and lower temperatures resulting in an 
increased average number of vertebrae.
3. The author (Itazawa) repeated the experiment using Channa argus 
(snakeheads), incubating eggs at different controlled temperatures. He 
confirmed the finding that the highest number of vertebrae occurred at 
intermediate temperatures, the number falling off for both high and low 
temperatures.
4. Note that the range of vertebral numbers that he found were from  56 
to 62, but there was extensive overlap. The differences in AVERAGE 
vertebral number from a large number of hatchlings examined (a total of 
roughly 4500) were less than one vertebrae. Thus, the effects were small 
and wouldn't, in my opinion, be noticeable as a marked decrease in the 
length of the fish.

Note also that this effect is one of the effect of temperature 
variations during the development of the egg, not the growth of the fry.

Some hobbyists have postulated that the shortening effect might be due 
to effects of lower temperature during the growth of the fry. This is 
possible, but could not, in my mind, be due to an effect on vertebral 
number. Low temperatures could effect the growth in length of the 
vertebrae, which potentially could have a large effect on total length 
of the fish. The reason I make that speculation is that modest effects 
on all the vertebrae would be cumulative and more likely to produce a 
noticeable effect that the addition or loss of one vertebra.

In summary, I think we are still without an explanation for the short 
back effect that some hobbyists have experienced.

Barry Cooper

-- 
Barry J. Cooper
Sweet Home, OR 97386


       
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