Date: 2 December 1998
From: SEAN TIBBETTS <stibbetts@cadmin.nsac.ns.ca>
To: AQUA-L@killick.ifmt.nf.ca
QUESTION:
We are inquiring about glass eel initial feeding (any species). Many of the same problems exist when attempting to feed marine fish juveniles (mortality, poor growth). In our lab we used frozen Artemia and were successful, however, it is quite costly for the producer to use. I was curious as to whether any labs or eel farms are using "live" feed (Artemia, rotifers, etc.) for initial feeding of glass eels.
Any information is greatly appreciated.
Sean Tibbetts
Graduate Student in Aquaculture
Department of Animal Science
Nova Scotia Agricultural College
P.O.Box 550, Truro, Nova Scotia
Canada, B2N 5E3
Tel: (902) 893-3951
Fax: (902) 895-6734
stibbetts@cadmin.nsac.ns.ca
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COMMENTS 1:
Live feed as you are mentioning might cause problems to your biofilters. Usually it reproduces itself within the filters and feeds on the biological lawn. The clarification performance is reduced then and starts fluctuating. We recommend to use frozen cod roe (fed in small frozen blocks). It works well, is hygienic and affordable.
Werner Gaus MD
MEGA FISCH GmbH
Alte Ploener Chaussee 3
24619 Bornhoeved
Germany
Tel: 49/4323/96.330
Fax: 49/4323/96.332
e-mail: Megafisch@t-online.de
Web: http://www.fishling.com/megafisch
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COMMENTS 2:
Live Artemia are produced in quantity for the ornamental fish market in Singapore (30% of world ornamental fish market). A major initiative by the Primary Production Department and Associates Aquarium has perfected the rearing process. Mr. Andrew Soh, Managing Director, (fax (65) 793-7796) produces about 700 kg a month and sells them in 30 g packets for Singapore $2.00 each. They are only used for feeding the smaller varieties of fish like guppies, discus, anglefish, etc.
Ross Heuchan
Director, Environment
Canada-ASEAN Centre
Singapore
e-mail: rossh@pacific.net.sg
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COMMENTS 3:
Most eel farmers in Europe use roe of cod or plaice for first feeding before dry diets can be used.
Gerrit Quantz
BUTT Marine Fischfarm
D-24229 Strande, Germany
Tel: 49/4349-383
Fax: 49/4393-506
e-mail: butt.fischfarm@t-online.de
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COMMENTS 4:
How is the roe prepared? Are all the eggs separate? Are they dried or frozen? Do they float or sink? Where and how are the eggs marketed?
Madelon Mottet, Ph.D.
Alaska-Southeast Bio-Research
Sitka Sea Farm
704 Sawmill Creek Blvd.
Sitka, Alaska 99835 USA
Tel: (907) 747 3862
Tel/Fax: (907) 747 0622
E-mail: madelon@ptialaska.net
http://www.ptialaska.net/ madelon/
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COMMENTS 5:
The ovary with the eggs prior to spawning is taken from the fish as a whole organ. The eggs have to be still in the egg sac. It is stored freshly frozen and is offered to the glass eel frozen on a swimming tray. The eel will pick off eggs while the mass is thawing. Such roe can be obtained from either fishermen during seasonal fishing on ripe cod (in North Sea during Jan-March) or from wholesaler, that are specialised on their product. it is important to get the right stage of the ovaries during the ripening: just before the eggs take up water and are ready for ovulation. At that stage the ovaries already become too soft and eggs are washed out during feeding. I suggest to get in contact with fishermen of the small scale coastal fisheries. When they slaughter their daily catch, roe can be collected at different qualities. Most common to use is cod, but it also works with that of some flatfish.
Gerrit Quantz
BUTT Marine Fischfarm
D-24229 Strande, Germany
Tel: 49/4349-383
Fax: 49/4393-506
e-mail: butt.fischfarm@t-online.de
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COMMENTS 6:
In Australia we have successfully used eggs of common carp as a replacement for cod roe in weaning Australian shortfin glass eels, Anguilla australis. We typically break the fast of glass eels with Artemia for a few days, once returned to the hatchery and upon being acclimated to fresh water. We then feed the carp roe for several days prior to finally being weaned on to a dry pelleted diet. Rate of weaning varies from batch to batch and can be as short as a few days or can take up to a few weeks. Presentation of the roe and associated feeding protocols follow the standard European protocols, otherwise as described in recent postings to the list (and below). This approach generally works very well for our Anguillid species and has now become fairly standard industry practice in this part of the world; particularly useful given that we have no shortage of carp!
Geoff Gooley
Mgr. Aquaculture Program
Marine and Freshwater Resources Institute
Private Bag 20
Alexandra, VIC 3714, Australia
Tel: 03/5774.2208
Fax: 03/5774.2659
G.Gooley@nre.vic.gov.au