Fish and Aquarium・Invertebrates｜🔴 Supplementary Column A: Water Quality and Water Body Management | Evidence chain

FAQ

When a fish looks ill, what is the first thing to do?

Test the water first, rather than looking for a disease name. Water quality abnormalities overlap heavily with several infectious diseases in their signs (gasping at the surface, rapid breathing, darkened colouration, refusal to feed, turning belly-up), the signs alone cannot separate them, and a water quality problem can be fatal within hours to a day or two. The order is ammonia, nitrite, nitrate, pH, dissolved oxygen and temperature; only after confirming that water quality is normal do you move to the common disease table and work through it.

魚が病気に見えるとき、最初に何をすべきですか。 — 病名を探すのではなく、まず水を測ってください。水質の異常と複数の感染症は症状が大きく重なり（水面での口ぱく、呼吸が速い、体色が暗くなる、餌を食べない、腹を上に向ける）、症状だけでは区別できません。しかも水質の問題は数時間から 1〜2 日で致命的になりえます。順序はアンモニア、亜硝酸塩、硝酸塩、pH、溶存酸素、温度で、水質が正常と確認できてはじめてよくある疾病表に進んで調べます。

When a fish looks ill, what is the first thing to do? — Test the water first, rather than looking for a disease name. Water quality abnormalities overlap heavily with several infectious diseases in their signs (gasping at the surface, rapid breathing, darkened colouration, refusal to feed, turning belly-up), the signs alone cannot separate them, and a water quality problem can be fatal within hours to a day or two. The order is ammonia, nitrite, nitrate, pH, dissolved oxygen and temperature; only after confirming that water quality is normal do you move to the common disease table and work through it.

When every fish in the tank goes wrong at once, what should be suspected first?

Suspect a water body problem first — insufficient dissolved oxygen, or elevated ammonia and nitrite — rather than infectious disease. Immediately dilute with a water change and stop feeding, check whether the bacterial population in a new tank is not yet established, and check whether the heater or other equipment has failed.

水槽の魚が同時に不調になった場合、まず何を疑うべきですか。 — 感染症ではなく、溶存酸素の不足やアンモニア・亜硝酸塩の上昇といった水体の問題をまず疑ってください。このときはただちに換水して希釈し、給餌を止め、あわせて立ち上げ直後で菌群が未確立でないかを調べ、ヒーターなどの設備が故障していないかを確認します。

When every fish in the tank goes wrong at once, what should be suspected first? — Suspect a water body problem first — insufficient dissolved oxygen, or elevated ammonia and nitrite — rather than infectious disease. Immediately dilute with a water change and stop feeding, check whether the bacterial population in a new tank is not yet established, and check whether the heater or other equipment has failed.

Do invertebrates have the same margin for error as fish when water quality swings?

No. Shrimp, snails and corals have a lower margin for error than fish when it comes to water changes, filtration and water quality swings; a swing of the same magnitude that fish can ride out may be more than invertebrates can survive. Sharp short-term swings in salinity or hardness also cause osmotic disturbance and abnormal moulting.

無脊椎動物の水質変動への許容度は魚と同じですか。 — 同じではありません。エビ、巻貝、サンゴは換水、ろ過、水質の変動に対する許容度が魚より低く、同じ幅の変動でも魚は乗り切れて無脊椎動物は乗り切れないことがあります。塩分濃度や硬度が短時間に激しく変動すると、浸透圧の失調や脱皮の異常も生じます。

Do invertebrates have the same margin for error as fish when water quality swings? — No. Shrimp, snails and corals have a lower margin for error than fish when it comes to water changes, filtration and water quality swings; a swing of the same magnitude that fish can ride out may be more than invertebrates can survive. Sharp short-term swings in salinity or hardness also cause osmotic disturbance and abnormal moulting.