cyprinid nutritional
requirements
From: owner-aqua-l@killick.mi.mun.ca
To: aqua-l@killick.mi.mun.ca
Sent: 22 September 2004
Question:
I have a few questions
for the fish nutritionists on the list.
We operate a relatively large zebrafish aquaculture facility, and are
considering revising our adult diet. Our current diet consists of Artemia
nauplii (~ 2nd instar) 3X a day, augmented with a flake food. However, the
design of our aquaculture system makes delivery of a dry flake food very
difficult and overly time consuming (large numbers of small tanks with
tight-fitting lids). The overall goal of this facility is high volume, high
quality egg production.
We are considering one of two remedies to the situation.
Remedy#1: Stick with the Artemia 3x per day and find a formulated/artificial
feed suitable for the species that can be mixed with water and fed in liquid
form without nutrient loss.
Question: Does such a feed exist?
Remedy#2: Abandon the idea of feeding a formulated food to round out the
diet, and instead enrich the Artemia with a commericial mixture, such as
selco.
Question: Would enriched Artemia alone be of sufficient nutritive value to
maintain high levels of fish health?
The bottom line is that we need to find feeds that 1) promote high levels of
fish health and 2) can be delivered in a liquid form.
Christian Lawrence
Brigham and Women's Hospital
Division of Hematology
Karp Family Research Laboratories, 06.004B
One Blackfan Circle
Boston, MA 02115, USA
Tel: 617.355.9041
Fax:617:355:9064
e-mail: clawrence@rics.bwh.harvard.edu
***************
COMMENTS
1:
Remedy #1. yes this feed exists. I use to work
with the INVE group in Ecuador, they have a Concentrate named BREED-S, you
have to specify that you are interested in the Concentrate, not in the
formulated feed, named BREED-S feed. This Concentrate allows you to
add water, and any other nutrient you consider necessary, but this conc is
very complete in nutrition for shrimp. For fish they have many options with
their Farms Nutrition Dept. The contact in America is WIM TACKAERT,
his e-mail is wtackaert@inve-us.com,
and the technical support is in charge of PhD, Peter Coutteau
(p.coutteau@inve.be).
Remedy#2.- The enrichment of Artemia is a very
known practice, with many advantages, feel free to ask Wim Tackaert for this
item too. I don´t think enriched Artemia is enough alone for keep
good health and nutrition, but a good quality of enriched Artemia, and a
good source of nutrients in a formulated feed are good complements. On this
topic Nick King could be of great help to, his e-mail is nking@inve-us.com
Fabian Jijon
e-mail: fabianjt@porta.net
***************
COMMENTS 2:
All dry diets, especially in the < 1 mm size range
for zebra fish, have nutrient leaching problems. You can make diets
that hold together but they will still loose critical water soluble
components (vitamins in particular). This is related to basic
diffusion theory where the relevant time constants are related to the square
of the particle dimensions ( t = K * X^2 -- going from a 5 mm pellet to a
500µ pellet will decrease the leaching time by a factor of 100 -- hours to
minutes).
If your systems are typical zebra systems, running
dry feed through your water distribution system will create massive
bio-fouling problem and potential opportunistic pathogen problems.
Cleaning valves on thousands of tanks could be a major maintenance
problem.
If you make a diet that doesn't leach, it won't be
attractive to the fish and they may not be able to digest it. This is
one of the contradictions in aquatic diets. What you put into the
water is not necessarily the same as what they eat, especially for small
diets and larval fish diets.
Option #2 using Artemia only is much more viable.
Salk Institute was using mainly Artemia for a long time, but are using a
little more of my dry feed formulation at the present time. Enriching
is a good idea, especially for vitamin C. With live rotifers for the
larva and live Artemia (enriched), you can go from egg to egg in 47 day with
zebra fish (Aquaneering rack system -- modified, 28ºC, 2ppt salinity, pH
7.2, auto feed 14 hr light, 100% Artemia past 10 days pf, 35 fish/l density,
wild type). If you modify the piping system for flushing, you can run
live Artemia through the water system. Live Artemia and live rotifers
will also go through the fluidized bed bio-filter systems and be recycled to
the fish (need to modify the SS control system).
Option #3: I have been using live rotifer on
zebra fish from larva to adult. These will go through the piping
systems and small valves and can be used in automatic feeding system.
I have been playing with a rack system with this concept and it looks
promising. I use Aquaneering tanks with screens and aeration behind the
screen and control the feed to the tanks by controlling the flow rate to
each tank then just add the rotifers to the system flow. Adult zebra's
will eat rotifers.
Live rotifers can just be purchased and then enriched
with some algae feed while being fed. We have been selling to local zebra
researchers and, in large numbers, to aquaculture hatcheries via FedEx/UPS
-- there are other suppliers. In terms of real biomass, zebra fish
facilities really don't have that much and the total feed requirement is
relatively small. However, the labor cost of getting the feed into the tank,
when you have thousands of tanks, is very high. The opportunity cost
of taking more than the minimum time going from egg to egg is the largest
cost of a non-optimal feeding protocol (cutting the egg to egg time from 70
to 90 days to < 50 days could increase the lab research productivity by
50+% with no significant facilities changes -- the million dollar impacts).
PS: We produce/sell about 75,000 zebra fish/wk and
feed 5 kg/day of live rotifers (wet wt) and a few kg/day of dry feed.
PS2: Most aquarium flake foods are flakey and not
publicly age dated (diets go bad and will actually create egg viability
problems long before they will kill a zebra).
Dallas E. Weaver, Ph.D.
Scientific Hatcheries
5542 Engineer Dr.
Huntington Beach, Ca 92649, USA
714-890-0138
Fax 714-890-3778
e-mail: deweaver@surfcity.net
http://www.ScientificHatcheries.com