Sudden depletion of oxygen

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Aquarium Advice Apprentice
Jul 14, 2023
I have kept fish now for 35 years, and have a stable mature 180L Juwel community tank. I cannot remember the last time any of my fish were sick, which is probably due to weekly maintenance including 35% water changes, and not overfeeding. I only feed 3 times a week. Most of my fish are 8/10 years old.

The purpose of this post is to warn other members of the importance of ensuring a good oxygen supply to the tank. In my tank the outflow pipe from tne Juwel pump is pointed up towards the surface of the water, so that it makes a ripple on the water surface to help oxygenate the water.

I had an emergency today. I had been away from home for probably 18 hours, and when i got back I noticed that the outflow pipe from the pump was on the floor of the aquarium. I can only imagine it may have been knocked off by one of my larger fish. More importantly my two beautiful 8 year old male Boesemani Rainbowfish lay dead on the aquarium floor.

I can only assume that with the pipe knocked off there was no ripple on the water surface, and the tank would slowly become depleted of oxygen. Boesemani Rainbowfish are particularly susceptible to low oxygen, and obviouisly did not survive. Other of my fish like Yellow Gourami's and Albino Corydoras can take in air by breathing air through their mouths at the water surface, and therefore were more able to survive. You might notice these fish suddenly dart up to the water surface for air.

Although my emergency came about through some sort of accident it just goes to show how quickly a tank can become depleted of oxygen, and the affect it can have on certain types of fish.
Lack of oxygen can kill fish pretty quickly. If you have a power failure, its not going to be lack of filtration or heat that kills them first, its going to be oxygen depletion.
Yes, sadly things happen when we least expect it or when we can't control it. Yours is a good reminder of having more than one oxygenation source so if one fails, the other at least helps delay any major problems. In my wholesale houses, I always used an air driven filter along side the recirculating system " just in case". Pumps break, filters and air stones clog, hoses come undone, etc. so having a backup is always a good idea. (y) (y)

Sorry to hear of your losses. :(
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