Ntchila brood stock collection in Malawi

I worked in Malawi as JICA (Japan International Cooperation Agency http://www.jica.go.jp/ ) expert in NAC (National Aquaculture Center in Domasi http://project.jica.go.jp/malawi/5241021E1/index.htm) from 2000 to 2004. The jobs were technical transfer of broodstock collection, seed production and juvenile rearing of carp, catfish and tilapia.

Ntchila (Labeo mesops) is very popular and abundant fish before like it figure show in coin. I hard that Ntchila gather and swing grasses at shore during spawning season. But we can't see in market except inside national park. We collected Ntchila at Shire River inside Liwonde National Park http://www.theplateau.com/malawi/liwonde.htm with fishing permission.

First thing to do, we visit fisherman village to get fisherman and bring to fishing area to drew a canoe. Fisherman set drift gill net on sunset and drew a net every an hour and it was done until late midnight. Brood fish should not have any damage, such as bleeding from the skin or fins and ensure that no scales have been removed. The large and more active fish should be selected which had total lengths greater than 20 cm and weigh more than 100 g. Purchased fish were kept in 40 litter plastic boxes, in a boat, with oxygen supply, oxygen had shown to have a better survival rate than aeration alone, and the water should be changed when it becomes contaminated. The fish was packed in doubled thick plastic bags (50 by 70 cm) each with 12 liters of water and 3 Kg of fish body weight. The plastic bags were tied with rubber bands after they were fully filled with oxygen.

When arrived the center, antibiotics were prescribed to the brood fish, the fish was soaked in an antibiotic solution (1 ppm of Oxytetracycline with water flow through) to minimize bacteria propagation due to any damage of skin and fins in order to enhance survival rates. Brood fish were transferred to the earth pond after sampling has been done in the hatchery, usually within three days.

I encountered a cloud of mosquito at middle of the river and it couldn't open eyes. I just put on rain coat and covered face while half an hour.

私は２０００年から２００４年にかけて、ＪＩＣＡ（国際協力機構http://www.jica.go.jp/）の専門家としてマラウイのＮＡＣ（National Aquaculture Center in Domasi http://project.jica.go.jp/malawi/5241021E1/home.htm）で働きました。活動内容はコイ・ナマズ・ティラピアの親魚採集・成熟促進・種苗生産・稚魚飼育の技術協力でした。

ンチラ(Labeo mesops)は通貨の絵柄に使われるほど、大衆魚で沢山いた魚です。かっては産卵期に水辺に集まり水草を揺らすほどす沢山いた魚だそうでが、今では国立公園でしか観られません。親魚採集は採捕許可を取得の上、リウォンデ国立公園（　http://www.dososhin.com/dictionary/malawi/　）の中を流れるシレ河で行われました。

まずは漁村に出向き、漁師をカヌーごと漁場に引張って行きます。日没に流し刺し網を仕掛け、毎時に網を揚げる漁を夜中まで続けました。親魚は鰭や皮膚からの出血が無いこと、鱗がとれていない事が条件です。また、活力があり全長２０ｃｍ・体重１００ｇ以上であることも大事です。買い付けた親魚は自分のボートにある４０Ｌタンクに移し酸素の通気をします。空気よりも酸素の方が生存は良いようで、タンク内の汚れた水を変えることも必要です。３Ｋｇの魚を１２Ｌの水を入れた二重ビニール袋（５０ｃｍｘ７０ｃｍ）に収容し、酸素を充満させ輪ゴムでしばり封をします。

センターに到着した魚は生存率を高めるために、抗生物質で薬浴（オキシテトラサイクリン１ｐｐｍで弱い流水）し傷ついた皮膚や鰭からの感染症を軽減させます。魚は３日後魚体測定をしてから、土池に移されます。

親魚採集中に蚊の大群に遭遇した事がありましたが、とても目を開けていられる状態ではありませんでした。私は合羽を着てフードを目深くかぶり、３０分ほどじっと耐えていました。