help me figure out why we are losing fish

[Fishionista]

Have you tested your water?

Yes

If yes, what is your ammonia?

0

If yes, what is your nitrite?

0

If yes, what is your nitrate?

10

If I did not test my water...

...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.

Do you do water changes?

Yes

What percentage of water do you change?

31-40%

How frequently do you change your water?

Every week

If I do not change my water...

...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.

We have been losing quite a few rummynose tetras lately, and also lost some otocinclus. This is a new tank, but it's currently cycled. With the otos we have lost, there has been no warning (we just find them dead on the substrate), but with the rummynoses they display certain behaviors a couple hours to a day or so before they die:

• rapid "gulping"
• lethargic behavior, not consistently swimming with the school
• sometimes they are at an odd angle in the water

Water parameters:

• ammonia 0 and nitrites 0
• nitrates ~10
• temp about 82 F
• ph 7.5 - 7.6
• GH 30
• KH 40

From what I've been reading online, the behavior we've been seeing is mostly likely due to poor water parameters (doesn't seem to be the case for us), low levels of oxygen (shouldn't be a problem since we have an air pump running connected to a sponge filter), some kind of parasite or illness, or stress.

Also possibly worth noting, we use well water here. Because there's no typical city tap water treatments or chlorine in our water, we don't tend to use water conditioner. In any case, it's been over a week since our last water change, and one of our rummynoses is currently displaying the "I'm gonna die" behavior and we lost another one a few days ago, so I'm not inclined to think it's a problem with our well water...but maybe it is? Maybe there's something we aren't testing for?

The fish do not show any outward signs of illness/parasite.

Ideas as to what could be wrong? Is there some kind of broad spectrum anti-illness/parasite medication we could dose the tank with that would handle a bunch of possible unseen problems?

In terms of stress, I don't think we are stressing our fish out any more than normal. The only thing I could come up with is maybe our rate of water flow is a little too strong? It's a 29g and we are running an AC 70 alongside the sponge filter. But to me this seems almost like a typical level of "overfiltration" and I don't think it would explain the loss of the otos. For the moment I've temporarily turned off the main filter and I'm just running the sponge, just in case.

I would appreciate any advice.

 

[Fishionista]

The GH and KH values are ppm, not degrees

 

[troublesum]

Where did you buy the Tetras and Otos from? If from a big box store (PetCo, PetSmart) maybe they came in with infections already
Besides that i have no clue. Maybe someone who knows more about infections and bacteria can help more

 

[Fishionista]

Where did you buy the Tetras and Otos from? If from a big box store (PetCo, PetSmart) maybe they came in with infections already
Besides that i have no clue. Maybe someone who knows more about infections and bacteria can help more

The otos all came from LFS. It's fairly reputable. The initial rummies came from the LFS and then we got some more from Petco some time later. But we've pretty evenly lost rummies from both Petco and LFS. Actually the Petco ones might be doing a bit better, oddly enough.

 

[Deadeye]

The pH is higher than what their preference is for, but that shouldn’t be a huge issue.
Otos need pretty well established tanks. They are biofilm grazers and need a lot of growth to be able to feed properly. I never really had luck with them (except for one when I wasn’t trying). As a whole, they tend to not be so hardy and wither away after a bit. I don’t think you’re doing anything wrong with them, they just don’t have a great track record.
As for the rummies, I don’t have any experience with them but I do recall hearing they aren’t the hardiest either. Do the dead fish look off at all? White patches, fuzziness, thin look? Neon tetra disease (microsporidians) is fairly common in a lot of tetras. It only spreads when they eat the fish that died from it. You can try pulling the dying fish before they die in the tank to see if it limits the spread.

 

[Chaitika]

I'd suggest turning the ac70 back on adjusting it to it slowest flow. That filter is not overwhelming the fish.

Ottos do not acclimate well from the importers and often stop feeding in captivity and then just fade into death. I always check their bellies before buying. If they're sunken, that's a sure sign they won't survive.

I find most tetras to be flimsy unless they've been in the store for a few weeks. I always let the store deal with the die offs before taking any home.

And then the water. Is the lfs on a different water source than you? How do you acclimate your fish before introducing them to your tank?

 

[Fishionista]

Deadeye, the dead fish never looks off unless it's been awhile since we found the bodies. The most recent one that just died looked outwardly fine. We removed it from the tank immediately.

Chaitika, I'll turn the AC 70 back on.

And then the water. Is the lfs on a different water source than you? How do you acclimate your fish before introducing them to your tank?

They are almost certainly on city water, whereas we are on well water. I am not sure what their water params are, but the way we acclimate is float the bag for 20ish minutes in the tank. Then we add some tank water to the bag. We do that a few times every 10 minutes or so and then add the fish to the tank, without adding bag water to the tank. If the bag gets too full at some point we dump out some of the bag water into the sink.

 

[Deadeye]

Sounds like a fine acclimation procedure imo. Do you have any other fish that are acting off?
If you can pull before they die it may help. It may not do anything, but if it is a disease that spreads post mortem it can be a solution.

 

[danotaylor]

Have you added any new decor to the tank?

If you haven’t done so already I would load the AC70 w fresh charcoal in case it is an unknown toxin in the water.