Why the high temperature?

Dallas Weaver, Ph.D. deweaver at gte.net
Mon May 14 09:59:16 EST 2001


I previously raised the question of why researchers are using such 
high temperatures (28.5 C) when the animals do very well and the 
human working conditions are much better at 25 C.  I ended up 
with a significant response indicating a lot of agreement that lower 
temperatures are preferred.  A few people brought up the standards 
problem and the fact that some more work would be required to 
develop a full set of development standards for lower temperatures.  
 The one argument in favor of the higher temperature was the claim 
that you can get faster egg to egg turnover time at the higher 
temperature.  Under conditions of perfect water quality, perfect feed 
(live feeds being the best) and low densities, the maximum growth 
rate temperature will usually give the shortest egg to egg time on 
non-seasonal spawners.  This is not true for all species of fish, 
where many species must go through a cool cycle before 
maturation.  

Has anyone proved that zebra fish have the shortest egg to egg 
times at 28.5 C, or have we just assumed that this is true????  

What are the real "egg to egg" times most laboratories are 
seeing???

How important is having the minimum time???

My reasoning for asking these questions stems from the possibility 
that we could shorten these times with better feeds and water 
quality.  I am thinking of live feeds produced under SPF (specific 
pathogen free) conditions and distributed to the laboratories.  If it 
looks like the potential market is large enough for a "clean" live 
feed, we could do the R&D necessary to develop the product.  Live 
feeds would have the additional advantage of not polluting the water 
until eaten and only require once per day feeding while achieving 
very fast growth rates.  

If you respond to the questions about egg to egg time, please 
include the number of mature zebras produced per year.  This 
would provide an idea of the feed requirements and the potential 
market for live feed.  

Thank You,

Dallas

PS: For the researchers who don't know who we are.  Scientific 
Hatcheries is a producer of live aquatic animals, most of which is 
live fish, which are used to feed other fish.  We adjust the fatty acid 
distribution of our product to match the requirements of our 
customers (marine fish require high levels of omega 3 fatty acids -- 
DHA, EPA).  Our customers, for the 20 million live fish per year 
that we produce, range from the pet hobby trade to major public 
aquariums and research laboratories working with animals that 
prefer/require live feeds.  There are a lot of aquatic animals, such 
as tuna and squid species, who use movement as a key to feeding 
behavior.  

We also provide zebra danios and embryos to researchers, as a 
sideline to production of about 50,000 to 100,000 zebra danios for 
the feeder and ornamental markets.   

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