琵琶湖産ナマズの飼育

2022年5月下旬、琵琶湖沿いの田んぼに遡上したナマズ。

その後産卵し、生まれたてのナマスの稚魚を田んぼから15匹ほど捕獲。
飼育してみることに。。。

Breeding catfish from Lake Biwa

In late May 2022, catfish migrated upstream along the rice fields along Lake Biwa. After spawning, we caught around 15 newly hatched catfish fry from the rice fields and decided to try breeding them.

ナマズの稚魚飼育開始

最初は30センチほどのプラスチックケースに藻だけ入れて飼育。
ナマズの稚魚のサイズは約１.5センチほど…
まだまだ、小さいので【冷凍あかむし】を入れると食べてる様子。

Starting the catfish fry breeding

Initially, we kept the catfish fry in a plastic container that was about 30cm in length with only algae as their food source. The catfish fry were about 1.5cm in size, and they seemed to be eating when we added “frozen red mosquito larvae” to their container.

ナマズの稚魚の共食い

ナマズを飼育した人の経験で、稚魚の間は【共食い】を繰り返すと聞いていたが。。。

あっという間に、同じぐらいだった稚魚が少なくなり
個体差が明らかに違う。。。。

最終的に15匹ほづいた稚魚が、1匹に！
しかも、最初【おたまじゃくし】みたいだった体がしっかり【ナマズ】になりました。

Cannibalism among catfish fry

Based on the experience of other catfish breeders, we were aware that the catfish fry tend to engage in cannibalism. Unfortunately, the same-sized catfish fry that we initially had quickly decreased in number, and there was a significant difference in their size.

In the end, we were left with only one catfish fry out of the original 15, which had developed from something that looked like a tadpole to a proper catfish with a golden body color. At first, we thought it might be an “Iwato catfish” due to its golden color. However, the actual “Iwato catfish fry” has a more square-shaped face, and its eyes are positioned further forward than those of a regular catfish.

体色が黄金なので【イワトコナマズ】かと思ってましたが…

実際の【イワトコナマズの稚魚】はもっと顔が四角く、
目の位置が普通のナマズに比べ前方にあるみたいです。

飼育1ヶ月

約1ヶ月で体長約5センチに！
そのまま【冷凍あかむし】を餌にしてましたが…
とうとう、ブクブクに藻を入れただけのプラスチックケースでは、水も汚れるので…

One month of catfish fry breeding

After about a month, the catfish fry grew to be around 5cm in length. At this point, we realized that the plastic container filled with algae and frozen red mosquito larvae was not sufficient, as the water quickly became dirty.

30センチ水槽

ろ過装置付きの30センチ水槽にお引っ越し！
そのまま、飼育を続け…
3ヶ月目ぐらいには、体長約12センチまで成長。
餌も【冷凍あかむし】から【小魚やエビ】にしたことで急成長した感じがあります。

We received d-points for our purchase at the d-payment point get mall

We then moved the catfish fry to a 30cm aquarium with a filtration system, and we continued to feed them frozen red mosquito larvae. By the third month, the catfish had grown to be about 12cm in length, and we had upgraded their food to small fish and shrimp, which led to rapid growth.

ナマズの餌

餌は、近くの池でガサガサにて【小魚やエビ】を採ってきて
別の水槽でキープしてあります！

Catfish food

We collected small fish and shrimp from a nearby pond to use as food for the catfish. We keep them in a separate aquarium.

飼育8ヶ月目

現在、ナマズの稚魚から飼育8ヶ月目になります。
【体長は約23センチ】
水槽ももう一度、20センチを越えるぐらいに60センチ水槽にお引っ越しし。
2度目の水槽チェンジになりました。

Eight months of catfish breeding

Currently, we are at the eight-month mark of breeding the catfish fry. They have grown to be about 23cm in length, and we have had to move them to a 60cm aquarium as they had outgrown their previous tank.

成長スピードが早くない？

あまりに成長スピードが早いので…
グーグルで【ナマズの成長スピード】と検索すると…

こんな答えが↓↓↓

成長のスピードは1年で15cm程度、2年で30cm程度大きくなり、飼育下のナマズと野生のナマズでは成長するスピードが若干異なる事が多いです。飼育下のナマズは野生のナマズに比べると、大きくならない事が多く、成長スピードも遅くなります。

と書いてありましたが…

通常、1年で15cm程度、2年で30cm程度なのに。。。
【ナマズのゴンちゃん】8ヶ月目で23cmって。。。
明らかに、私の飼育している【ナマズのゴンちゃん】は成長スピードが早すぎないですか？
もしかして？いやいや。。。

でも、このまま育てば、また水槽を大きくしなくてはならないですね。

Is their growth rate too fast?

Their growth rate has been extremely fast, and we were curious if this was normal for catfish. When we searched “catfish growth rate” on Google, we found that they typically grow around 15cm in the first year and 30cm in the second year. It is common for catfish bred in captivity to grow slower and not as large as their wild counterparts.

However, our “Gon-chan catfish” grew to be 23cm in just eight months, which seems unusually fast. Perhaps we are mistaken, but if they continue to grow at this rate, we will have to upgrade their tank again soon.