Transferred fish to new tank... bobbing near top

Today I moved my 6 glofish (skirt) tetras from a 10 gallon to a 20 gallon tank. I used the same substrate and included some filter media from the 10g in the 20g to bring over the beneficial bacteria. I use water from a filtered source with no chlorine, ammonia, etc. I tested the water and all the levels are in good ranges (0 nitrite, less than 10 nitrate, etc). Temp is 78 degrees. All the normal stuff the fish are used to.

They have been doing fine for the past several hours but I just noticed that a few of them are all congregating near the top back left corner of the tank kind of bobbing their mouths near the surface. I am going to try to include a video. When I started filming the flash came on and they kind of dispersed from the light.

I can't figure why they'd be doing this near the surface. It seems they are trying to get more oxygen but the water quality is good. Any thoughts as to what else might be causing this?

I did have the HOB filter flowed turned fairly low (it's noisy) so could that possibly be a reason? I just cranked it up to a higher flow to see if that makes a difference.

Any help is appreciated. I lost one of the fish earlier this week in the 10g tank so hoping nothing goes wrong with the remaining fish. Thanks.

Sorry forgot to attach. I have 1 video and 1 pic. Sorry for the bad quality - I am not turning the lid light on yet so as not to stress them out more. I am not able to get the video to upload for some reason. Sorry!

There is one (the blue one) that seems to be doing it the most.

I think your hunch of it being an oxygen thing could be what's going on. I would lower the water level in the tank by a half inch or so and turn the filter all the way up. You should get a real good waterfall (which will drive you nuts noise wise). But that should resolve the issue within an hour or two if it is an oxygen thing. If it gets resolved, I'd then run the filter on full for the next few days, and add an airstone if the noise is driving you nuts. Another way would be to add plants, since they generate oxygen and will help in that regard. I would test for nitrites and ammonia again just in case, though with you moving everything over from the other tank it should be fine.

Oh, also, if the problem is resolved by bedtime, do bring the water level back up but leave the filter on full so it doesn't keep her up all night

mcordelia said:

I think your hunch of it being an oxygen thing could be what's going on. I would lower the water level in the tank by a half inch or so and turn the filter all the way up. You should get a real good waterfall (which will drive you nuts noise wise). But that should resolve the issue within an hour or two if it is an oxygen thing. If it gets resolved, I'd then run the filter on full for the next few days, and add an airstone if the noise is driving you nuts. Another way would be to add plants, since they generate oxygen and will help in that regard. I would test for nitrites and ammonia again just in case, though with you moving everything over from the other tank it should be fine.

Oh, also, if the problem is resolved by bedtime, do bring the water level back up but leave the filter on full so it doesn't keep her up all night

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Thank you for weighing in. So.... I think the filter that came with the kit was a piece of crap. It's the TopFin 20 gallon kit from PetSmart. I should have known better. So I took that filter off. I have 2 Marina (I think it's a Fluval brand?) filters - one for 15g and one for 10g. I have BOTH of them on the tank right now opened full throttle. I seriously love these filters - they are so quiet. I had it on the previous 10g and it kept the tank crystal clear and water quality was always great.

I did also lower the water. It was all the way at the top of the tank. I took it down about an inch.

So, the good news .... I have the 2 filters going and so far 4 of the 5 are no longer up at top with their mouths at the surface for air. The not so good news: I have not been able to locate the blue one (the one that seemed to be having the most trouble breathing earlier). He is the hardest to see against the black background so I'm hoping he's just recuperating behind a plastic plant or something. I don't want to blast the room overhead lights to find them as the fish are so stressed already.

Hopefully by morning I'll see little blue. I don't want to lose 2 fish in a week! It's seriously shaking my confidence. But I have learned my lesson about buying cheap aquarium stuff. Never again!

Thanks for the heads up, since I have the same filter. I am surprised that it is THAT bad, considering you only have 6 fish in there!

I'm glad you took action and had the other filters available to switch out. I'm making a note to run an airstone in my 20 when I add fish to it, at least to be on the safe side!!

Not sure what area of the US you are in, but if you have an LFS anywhere close by, you could call ahead and see if it's worth the drive for some hornwort or similar, since I think it could help stabilize some of the water parameters and prevent future issues (to an extent). Another option is ordering online, though with winter coming.... I'll post in my plant thread that has probably gotten buried by now when I receive my plants this week on what my experience ordering plants online for the first time is, that'll hopefully also give you some info if that's a direction you want to go in

mcordelia said:

Thanks for the heads up, since I have the same filter. I am surprised that it is THAT bad, considering you only have 6 fish in there!

I'm glad you took action and had the other filters available to switch out. I'm making a note to run an airstone in my 20 when I add fish to it, at least to be on the safe side!!

Not sure what area of the US you are in, but if you have an LFS anywhere close by, you could call ahead and see if it's worth the drive for some hornwort or similar, since I think it could help stabilize some of the water parameters and prevent future issues (to an extent). Another option is ordering online, though with winter coming.... I'll post in my plant thread that has probably gotten buried by now when I receive my plants this week on what my experience ordering plants online for the first time is, that'll hopefully also give you some info if that's a direction you want to go in

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So, the TopFin filter has this propeller thingy that came apart when I was getting it ready to go in the tank (not sure what it's called but it looks like a little propeller). So I put it back together but it just seemed like a flimsy filter overall. And the water flow noise was LOUD. The previous tank and filter I had (Marina) was so quiet I couldn't tell the filter was running. Which was great because it's right next to my daughter's bed.

I had turned the flow way down on the TopFin filter because I didn't think my daughter would be able to sleep tonight with the noise. I am not sure if that caused the issue with the oxygen levels or if it's just the quality of the filter overall. I also think the filter is not quite sufficient for the tank size. The Marina tank I had was a 10g and it came with a 15g filter. This is a 20g filter so I'm thinking the capacity may also have something to do with it. Just a couple of semi-educated guesses since you are setting up the same tank.

I used to have a tetra filter on my 55g 15+ years ago, it was relatively similar to this one, though it's possible that the impeller was a better design. I ran the top fin for a few days last week as I was leak testing the tank, and I agree it's pretty loud. Mine did not make water noise since I filled the tank all the way up to the bottom of the "lip" of the filter outlet, but some part rattles against some other part somewhere in mine, and it's kind of annoying. I think it's that little hinky "cartridge indicator" or something. Granted, I was just running mine with the blue thing in it since I didn't want to get the carbon wet, so maybe once I put the cartridge in it will either get better or worse . I figure I'll run the carbon for a month or so and then just slash the pad and get as much of it out as I can and call it good. Depending on how I like the filter over the long term I'll either switch it out completely to a sponge filter or when the cartridge falls apart I'll just toss some foam in there. If nothing else, it'd make a good container for a pothos plant - it can be set on a timer so it only flows during the day

What are you using for filter media?

Would the noise be from trapped air?

Are you thinking of the gurgling noise that a filter makes when it's first turned on that then decreases over time? Or is there a different kind of trapped air that occurs? I am not sure if the intake tube fills fully at the top since it's relatively tall compared to the "power" of the impeller, but I've never had a HOB that I had to try and fill the tube at the top.... I don't even know if that possible; how would you get the water to stay up there when you turn it right side up and put it into the impeller shaft...? My old tetra HOB had a much smoother shaped intake tube at the top, and as long as there was water in the filter it filled the tube area fully, since it wasn't that high relative to the location of the impeller. Maybe I'm overthinking what you mean

ClownLurch said:

Would the noise be from trapped air?

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It was water splash noise - no matter the level I set the flow. The filter itself wasn't noisy in terms of motor. It just made a lot of splash noise even when I adjusted the water level in the tank.

Oh interesting, mine did not make any splash or ripple noise. I have my water halfway inside the black rim on the tank, what level did you have your water at?

by the way, wanted to update on my filter - it's now just making a hum. Yesterday when I was putting the sand in I took the impeller out and noticed that it attaches to a bracket, and the bracket has grooves on the bottom of the filter for it to sit in. I think that was loose which was causing the rattling noise. I have the water level at the bottom of the outlet, and it's not making any gurgling or other noises, just a hum. I also added the filter cartridge finally since I'm expecting my plants to arrive tomorrow. Overall, it makes less noise than the stupid hum of my computer monitor that is on its way out