Hi Everyone,
Thanks in advance for your advice. I did a water change on my tank yesterday during the day and woke up this morning to a tank with a lot of dead fish, and the rest gasping at the surface. I've since turned the lights on to get the plants to produce O2 and also added a bubble maker (which isn't always on, but I keep in reserve if needed) and the remaining fish are now breathing normally. Given that the fish were gasping at the surface and the problem has been fixed by taking the aforementioned steps I am pretty sure that this had to do with some sort of oxygen shortage. Since something similar happened about 6 months ago following a water change (also overnight when the lights were off) I am certain that this event occuring with a water change is not a coincidence. Can you advise on why this is happening?
Before I go on, some facts:
- 90G established tank full of 2 year old rainbowfish.
- No, I do not inject CO2
- My tank is a low tech tank that is heavily planted -- lots of moss, vals, java ferns, crypts, and more moss
- I run dual Fluval 406 canister filters. Filtration is fully cycled, and I have not cleaned either canister so recently that this would be the cause.
- I do a water change once per week, usually about 30% but yesterday was probably more like 40%
- When I do a W/C I tediously fill buckets from a bath tub to replace water -- I do this because I add Seachem's dechlorinator (Prime) directly to each bucket before pouring back into the tank. I also make sure the temperature is about even with what's already in the tank.
- As of last night when the tank lights were still on, all the fish were fine. I know because I fed them while "distracting" my infant son with their bright colors... there was no gasping at the time (I have learned to look for this after a w/c).
So, again, seems like something correlated with night time (plants respiring CO2?) following a water change. Can someone explain why this is? And can someone explain why this doesn't happen after every water change (which I do weekly)? I've heard about this in tanks with CO2, but not otherwise.
Thanks!
Thanks in advance for your advice. I did a water change on my tank yesterday during the day and woke up this morning to a tank with a lot of dead fish, and the rest gasping at the surface. I've since turned the lights on to get the plants to produce O2 and also added a bubble maker (which isn't always on, but I keep in reserve if needed) and the remaining fish are now breathing normally. Given that the fish were gasping at the surface and the problem has been fixed by taking the aforementioned steps I am pretty sure that this had to do with some sort of oxygen shortage. Since something similar happened about 6 months ago following a water change (also overnight when the lights were off) I am certain that this event occuring with a water change is not a coincidence. Can you advise on why this is happening?
Before I go on, some facts:
- 90G established tank full of 2 year old rainbowfish.
- No, I do not inject CO2
- My tank is a low tech tank that is heavily planted -- lots of moss, vals, java ferns, crypts, and more moss
- I run dual Fluval 406 canister filters. Filtration is fully cycled, and I have not cleaned either canister so recently that this would be the cause.
- I do a water change once per week, usually about 30% but yesterday was probably more like 40%
- When I do a W/C I tediously fill buckets from a bath tub to replace water -- I do this because I add Seachem's dechlorinator (Prime) directly to each bucket before pouring back into the tank. I also make sure the temperature is about even with what's already in the tank.
- As of last night when the tank lights were still on, all the fish were fine. I know because I fed them while "distracting" my infant son with their bright colors... there was no gasping at the time (I have learned to look for this after a w/c).
So, again, seems like something correlated with night time (plants respiring CO2?) following a water change. Can someone explain why this is? And can someone explain why this doesn't happen after every water change (which I do weekly)? I've heard about this in tanks with CO2, but not otherwise.
Thanks!