One of my danios is showing excessive buoyancy. It appears healthy and active, but slowly floats to the surface when it stops to rest. I noticed it this morning floating among some salvinia roots. The other danios are behaving normally. Here's a video of the fish floating:
Here's a video of the healthy(?) danios:
Here's the history of the tank:
2021-12-12
Bought a 20 gallon tank, filled with water and gravel, added 6 stem plants and two bits of Salvinia, dosed the tank with two spurts of Easy Green. Started a sponge filter. The tank is lit with an 800 lumen bulb directly above the lid on a 12 hour photocycle.
2021-12-19
Added 6 danios to the tank along with a cup of Fritz Zyme 7. Danios surf the glass, eventually settle down in the darkest corner under some plants.
Added half a cube of frozen daphnia, this sank to the bottom, fish weren't interested in eating it.
Water parameters in the tank were as follows:
Nitrate 10 ppm
Nitrite 0 ppm
Hardness 300 ppm
Buffer 60 ppm
pH 7.6 ppm
Chlorine 0 ppm
Temperature 70 F
Water parameters in the store bag were as follows:
Nitrate 10 ppm
Nitrite 0 ppm
Hardness 0 ppm
Buffer 60 ppm
pH 6.4 ppm
Chlorine 0 ppm
The plants are generating new growth but there's no algae yet.
2021-12-20
After I turned down the light the danios emerged from the dark corner, patrolled the tank, grabbed some food from the top. I turned the light back up to get plants growing more quickly.
Dropped a few grains (like 6) of Xtreme nano, the fish didn't notice or aren't interested in eating it.
pH is down to 6.8, other parameters are stable.
2021-12-21
Dosed one spurt of Easy Green.
Water parameters are stable.
Dropped a few grains (like 6) of Xtreme nano, the fish didn't notice or aren't interested in eating it.
Fish continue to hang out behind the plant, occasionally patrol or chase each other.
2021-12-22
Thought I smelled ammonia but I don't have a test kit.
Water parameters are stable.
Fish continue to hang out behind the plant, occasionally patrol or chase each other.
Dropped a few grains (like 6) of Xtreme nano, the fish didn't notice or aren't interested in eating it.
Added a nerite snail to deal with any uneaten food.
2021-12-23
Dosed one spurt of Easy Green.
Water parameters are stable.
Fish continue to hang out behind the plant, occasionally patrol or chase each other.
Dropped a few grains (like 6) of Xtreme nano, the fish didn't notice or aren't interested in eating it (or are waiting 'till I leave?)
Nerite snail is slowly moving.
In the afternoon I found one fish floating among the Salvinia roots.
I moved the sick fish to another tank that I'd set up to grow plants more quickly. The new tank has a pre-set heater that's somewhat warmer than the main tank. The sick fish is darting about being distressed and floats the surface when it stops to rest.
I'm about to go out of town for a few days. What should I do to give the remaining fish the best chance of survival? I did a 50% water change in the main tank, added another splash of Zyme 7, and floated a black planter basket to give them more cover.