16 Apr
2019
16 Apr
'19
1:15 p.m.
From: Ram C. Bhujel <bhujel(a)aarm-asialink.info>
Sent: 16 April 2019 14:06
To: William Leschen <william.leschen(a)stir.ac.uk>
Subject: Re: Problème de mortalité d'alevins de clarias
Alexandre,
You said, "Our water has a pH of 5.3 and declared suitable for fish farming by a
laboratory of water chemistry".
Question1 - Do you think pH 5.3 is suitable for fish farming?
I don't think so. I would suggest to raise the water pH above 6.5, but keep below 9.0
by using lime.
Question2 - does the laboratory of water chemistry has experience of fish farming?
I thought laboratory of water chemistry gives you the test results only. You are the one
who should know what pH is good for your fish.
Lab test should have other parameters as well which can affect survival.
Are you sure the fry did not die because of cannibalism?
SEE MANY OTHER REPLIES TO THIS ON THE DAILY UPDATED SARNISSA FACEBOOK SITE VIRTUALLY
ALL SAYING pH OF 5.3 FAR TOO LOW FOR HATCHERY PRODUCTION OF CLARIAS JUVENILES
https://www.facebook.com/sarnissaafrica/
En francais
Alexandre,
Vous avez dit: "Notre eau a un pH de 5,3 et est déclarée apte à la pisciculture par
un laboratoire de chimie de l'eau".
Question 1 - Pensez-vous que le pH 5,3 convient à la pisciculture?
Je ne pense pas. Je suggérerais d'élever le pH de l'eau au-dessus de 6,5, mais de
garder en dessous de 9,0 en utilisant de la chaux.
Question 2 - le laboratoire de chimie de l'eau a-t-il une expérience de la
pisciculture?
Je pensais que le laboratoire de chimie de l'eau ne donnait que les résultats des
tests. Vous êtes celui qui devrait savoir quel pH est bon pour vos poissons.
Les tests de laboratoire devraient également comporter d’autres paramètres pouvant influer
sur la survie.
Etes-vous sûr que les alevins ne sont pas morts à cause du cannibalisme?
Best regards,
Ram C. Bhujel
Director, Aqua-Centre
Research Associate Professor
SERD, Asian Institute of Technology (AIT)
PO Box 4, Klong Luang, Pathumthani 12120
Tel. +66(02) 524 5222 (O), 081 734 6934 (M)
Email: Bhujel@ait.asia<mailto:Bhujel@ait.asia> or
Director@aqua-centre.org<mailto:Director@aqua-centre.org>
---
We offer 1-yr professional master's program in "Aquaculture Business
Management", short-term training on tilapia farming and various other subjects, pls
see at: Aqua-centre.org
On Tuesday, April 16, 2019, 7:12:42 PM GMT+7, William Leschen via
Sarnissa-african-aquaculture
<sarnissa-african-aquaculture@lists.stir.ac.uk<mailto:sarnissa-african-aquaculture@lists.stir.ac.uk>>
wrote:
Translated from SARNISSA French forum – can you help them ?
Mortality problem of clarias fry
We are a hatchery based in Lomé, Togo, operating since 2015. It must be said that the
first two years were very difficult to keep the fry alive. But since 2018 we have
obtained a very good survival rate of up to 75%.
It turns out that since January 2019 the trend has reversed with high mortality rates,
although we have not changed our trials or systems
At the last insemination we had an hatching rate of about 80% with the following
observations:
Usually already on the 2nd day of hatching the majority of the larvae manage to rise to
the surface. But for these larvae it is now just very few that come to the surface. Even
after 4 days of feeding (with Coppens) the fry lurk in the bottom of the basins almost
motionless as if struck with lethargy and they die in large numbers.
In principle, usually the death en mass is observed in the first 5 days of feeding and
is reduced enormously between 10 and 12 days from the appearance of the supra branchial
organ. But with the new situation even after 12 days the fry continue to die.
Our water has a pH of 5.3 and declared suitable for fish farming by a laboratory of water
chemistry; all the tanks containing the fry are equipped with air stones fed by an air
compressor; there is a 24-watt sterilizer in the water circuit that returns to the
hatchery; the water is renewed 4 times a day; every morning and evening we siphon waste
and dead fry; the food distribution is rationalized to avoid deposits in the bottom of the
tanks.
Has anyone ever observed such a mortality situation where systematically the fry stay and
stay at the bottom without really surfacing?
Thank you for educating us from your different experiences.
Hatchery Promoter
AHOCOU Koba
Tel: 00 228 90 22 15 83
From: AHOCOU Alexandre K <alexahocou@gmail.com<mailto:alexahocou@gmail.com>>
Sent: 12 April 2019 22:38
To: sarnissa-french-aquaculture Mailing List
<sarnissa-french-aquaculture@lists.stir.ac.uk<mailto:sarnissa-french-aquaculture@lists.stir.ac.uk>>
Subject: Problème de mortalité d'alevins de clarias
Bonjour monsieur l'administrateur
Je viens par la présente solliciter votre accord afin que que les membres de la plate
forme puissent se pencher sur notre problème de mortalité d'alevins décrit dans le
fichier attaché.
Merci infiniment
Alexandre AHOCOU
Promoteur de l'Ecloserie les Poissons d'Afrique
tél : 00 228 90 22 15 83