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Fish Dying in North American Native Tank


Registered Member
After setting up my 60 gallon aquarium, cycling it, and adding plants and driftwood, I attempted to add fish over the past three weeks.

The first time, I added a school of about two dozen bluntnose minnows (these are the xanthic strain bought from a LFS.) I lost about eight minnows before the population stabilized. They all seem energetic and healthy now.

I waited a week, and then attempted to add 3 wild caught pumpkinseed fish, each about 3-4 inches. It's only been overnight, and I've lost two. The third seems lethargic and stays at the surface, gasping. They were introduced by sitting in an aerated bucket of lake water, and I slowly added some aquarium water over an hour's time. Then I netted them out and released them into the tank. My aquarium is a cold water, room temperature setup, so the bucket water was the same temp. as the aquarium.

I really hate losing fish, even more so when I can't find the cause. Under state law, I can't just put them back in the lake if they are struggling, either. Before attempting to introduce any more wild caught fish, I'd like some opinions from more experienced aquarium keepers. What is going on?

*FYI: I live in Michigan and have a valid wildlife collection permit.*

Aquarium details:


-60 Gallon Glass Aquarium (36x18x22)
-Eheim 2237 Canister Filter (Spray bar located just above the surface)


Jungle Start Right after every water change. (Well water with softener running)


-NH3: 0ppm
-NO2: 0ppm
-NO3: 0ppm
-PH: 7.6
-Temp: 65.6 F


-Vallisneria americana
-Elodea canadensis
-Potamogeton robbinsii
-Fissidens fontanus


Aquarium Gravel Substrate
Driftwood (Locally found, boiled, and saturated for use. No idea what type of tree, other than it's a hardwood)


AC Members
Sometimes it is not about the water we have them in. It is about the water that they came from. With that it can make adjusting difficult for some fish.


Eheim User
Your tank isn't cycled since you are showing zero nitrate so that may be the culprit.


AC Members
Dee, I kind of ruled that out because some of the minnows survived and seem robust, plus he waited another whole week before adding other fish. Unless the tank has not cycled enough to handle the extra fish.


Registered Member
The tank is cycled. I did a fishless cycle with pure ammonia added to 4 ppm, and added Tetra Safe Start. A week later I was reading 0ppm on NH3, NO2, and only 5 ppm for NO3. The tank is heavily planted, and I recently did some 25% water changes.

I think I figured out what was going on. When I took the pH and temp of the lake, I neglected to do a gh/kh test to compare it to my aquarium. Just finished testing the lake, my aquarium, and my tap water with the water softener bypassed. I decided to do a 60% water change using unsoftened water to try to match the lake. I'll wait a few days, and do another large water change to be rid of the remainder of the softened water.

Aquarium (Filled previously with softened water)
pH: 7.6
gH: 0
kH: 240

pH: 7.6
gH: 180
kH: 180

Unsoftened Water
pH: 7.6
gH: 180
kH: 180


No freelancing!
Planted tanks will quite frequently have 0 nitrates--the plants consume nitrogen in all it's forms, and most plant tank keepers add nitrates to feed the plants.

Testing the water to see what the difference is chemically would be a good starting point. If possible, collect smaller fish, since juveniles will adapt more readily than adults. Make sure there is adequate agitation in the tank, as well, since low oxygen levels can be very stressful.