PLEASE HELP Fish Gasping for air

[wesleydnunder]

I've seen this happen before, and prime wasn't always associated with it...winter was. In warmer times of year, we don't have to temper the cold water with hot before adding it to the tank; only in winter do we have to do this, when using tap water. Hot water contains less oxygen than cold water. In a tank-type water heater, much of the oxygen in water is driven out of solution by heating it to 120F (avg. thermostat temp setting of water heaters). When we put this oxygen-depleted water into our tanks, it takes a while for it to reacquire its dissolved oxygen. This is why the fish aren't gasping two days after a water change, just in the first 24 hrs following one. So, prior to a water change, the movement of water in the aquarium maintains an amount of dissolved oxygen sufficient for the fish. When we drain 50% or more of this water and replace it with oxygen-depleted water the fish feel it immediately and respond right away. This is another arguement for keeping relacement water in holding vessels for at least 24 hrs prior to a partial water change.

Mark

[finfan]

mark, that makes complete sense and i think that resolves this mystery for me, instead of just turning the cold water, i did add hot water (from tap) with cold water (from tap) to bring temperature to a level similar to my tank (about 80 degrees) because the cold water from tap is way too cold during winter time, i didn't know hot water oxygen content is lower than that of regular/cold water, you live you learn, at least now that i know the source of the problem, i can do something about it, so maybe i will do a 20% water change with just the cold water from tap because storing it won't solve the water temp. issue since that would still be pretty cold, so in my case i was making it worse for them as i made additional changes... poor things... i feel terrible putting them through this... :(
thanks so much for this info

[wesleydnunder]

Storing the water in a vessel at room temp for 24 hrs or so will allow it to warm to room temp. Addition of an air stone or power head to the vessel will ensure good movement during the holding period and further speed the warming process.

I first noticed this occurance years ago when, during the winter, everything in the tank was covered in bubbles after a water change, and the fish were gasping. After some reseach on the subject, I changed how I do my tank maint. in the winter and it hasn't been an issue since.

Mark

[greg_tsam]

I always run my water and estimate the temp in the tank and the temp of the tap before refilling.

[edmlfc]

Wow! That's intresting. I never even thought about that. I knew when you riased the temp in the water you had to add an airstore but I never thought about when doing a water change during winter it would have that kind of impact on the fish. I'll have to rethink my water changes too.

[finfan]

update, i did a 15% water change using only cold water from tap using prime and flourish excel and there were no issues, i guess that points towards the warm water theory, i guess i have to wait till summer time to do 20%+ water changes!