(Please ignore wood biofilm lol)
I’m trying to figure out what’s going on with my fish and could use some help troubleshooting.
Over the past few days my fish have been gasping at the surface. I initially assumed it might be an ammonia spike, but I haven’t been able to confirm that or figure out what’s causing it. I’ve been dosing Seachem Prime and doing large water changes. I even did about an 80% water change a few hours ago. The fish improve temporarily, but the issue keeps coming back.
Tank details:
• Tank is about 4 weeks
• 11 gallon tank
• 12 mosquito rasboras
• 2 clown killifish
• 2 nerite snails
• Co2 has been off for about two days
Most of my water tests are reading normal, but my test kit is slightly expired and I’m waiting on a new one arriving tomorrow, so I can’t fully trust the readings right now.
Things I’m trying to figure out:
• Could this still be ammonia even after large water changes?
• Could strong flow or poor surface agitation be causing low oxygen?
• Is it possible something in the filter or media is causing stress when it’s running?
Any advice or ideas of what I should check next would be appreciated. I want to avoid stressing them further while I figure this out.
Posted by eldovo
15 Comments
Looks like they are grazing at the surface. As long as they aren’t gasping, or have any rapid gill movements, it seems to be normal behavior
Is your tank cycled fully? Also yes the surface does need agitation for oxygen transfer. What kind of filter are you using?
Probably an oxygen issue, check to see if your filter is adding enough oxygen to the water or add a bubbler
Nitrite poisoning causes gasping at the surface so if it is a cycle issue it is probably nitrites. I don’t know fish diseases well enough to say if it’s the most likely universally though.
The bad news is nitrites bind to the hemoglobin which means surface gasping doesn’t actually help anything. Nitrites are dangerous and 4 weeks into a heavily stocked tank sounds just about right for a spike.
Also check the heat, hot water holds less O2
since you pump Co2, you might be lacking oxygen. Try air stoning it and see if they return to normal
Nothing you’re describing immediately jumps out to my as an oxygen issue. You’ve already turned off CO2, which would be the biggest risk. They’re small fish found in slow moving waters so they don’t need high oxygen. Mine do absolutely fine with very stagnant surface water (because of all the floaters) and an hob. In an abundance of caution you can try adding a bubble bar to add additional circulation/oxygen exchange but I would be very surprised.
Your stocking doesn’t sound very dense and they really don’t have much bioload (aqua advisor tends to over estimate). I would be very very surprised as well if you’re having a massive ammonia spike you can’t see. The only thing I would check for is if there’s a large amount of rotting vegetation. Sometimes this can cause rapid oxygen depletion and/or ammonia spikes.
If you dim the lights, do they still act like this ? That’s the only thing that sticks out to me. Mine tend to behave a lot weirder when the light is too bright. My other concern would be if they have an illness. Sometimes ich can present as surface gasping if the cysts are more in the gills than the body (although if that was the case you would have seen rapid deaths by now).
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Not cycled. You should be checking ammonia, nitrites, nitrates daily and treating with prime and doing water changes per fish in cycling protocols. Get a bubbler/air stone. Your fish are in trouble.
i will say for the clown killis in particular: they just like to hang out in the top third of the tank especially right at the top and graze, it’s normal for them
I breed clown killis and can confirm they love to hang out at or about 2-3” below the surface. The only times that I see them doing something else is when they’re hunting meiofauna or laying and fertilizing eggs.
ETA: The other fish are generally mid-column, I’d recommend a water change.
I don’t see any breaking of the surface tension of the water, could also be lack of air in the water, i see the CO2 tester on the side so if you’re putting too much CO2 and no air exchange then you could be suffocating your fish
Your fish gills seems to also be very inflamed.
dial your CO2 down and get some more aeration in there
People mentioned o then, that water surface looks very still
nitrite poisoning seems like a likely culprit to me. Seachem’s Prime can bind to it as a temporary remedy to prevent further intoxication but it won’t fix your biofilter or cure the fish’s existing nitrite poisoning. you can use prime at 5 times the regular recommended dosing every 24-48 hours.
If you turned off the CO2 it is likely that you have low oxygen level in the tank.
Bacteria, plants, and your fish all consume oxygen. Oxygen needs to enter the tank or else it becomes a stagnant underwater grave. It can only enter from the surface. In our natural world, oxygen enters rivers and the ocean via surface agitation. The waves crashing into the air causes bubbles. Waterfalls are an easy one to get good oxygen.
And so it is moving water. All our fishes CRAVE and need moving water. But when they are trapped in our aquariums, we humans tend to tone down that water movement by a lot. Nothing in the hobby has anything close to what a crashing wave or rushing water going through rocks can do for a system.
get some oxygen in there. a HOB or turn your outflow to the surface.