I just stocked a freshly cycled 20 gallon planted tank with three dumbo guppies, one lively panda garra, and 10 shrimp -- 5 baby amano and 5 baby cherry. First time this tank has had anything in it other than the hitchiking bladder snails from the plants.
One of the guppies was weaker than the other two from day one (Thursday). I thought maybe it was stress, so I left it alone, but it didn't get any better the next day (Friday). If anything, it looked worse. On Saturday, I put it in a newly set up hospital tank. I didn't have any meds, so I dosed the tank with aquarium salt, which I did have. The guppy continued to decline on Saturday, developing pink-ish red spots along its body. Google told me the red might be an ammonia burn, but my API master test kit AND API ammonia strip test both said that the ammonia inside the hospital tank was at 0 (the water test was hard to distinguish between 0 and 0.25, but it was more yellow than green). Just to be safe, I did a 20% water change in the hospital tank early Sunday afternoon anyway. In retrospect, I think the water change might have been a mistake, because the sick guppy took a nose dive right after that -- literally and figuratively. The water change was about 12pm on Sunday; the guppy was dead by 4pm. 😞
Alright. Now to my main question. Of the three remaining fish -- two more dumbo guppies and a panda garra, the panda and one of the guppies seem totally happy and healthy, very lively. But the last guppy doesn't seem very strong. He's still swimming around, but sometimes (maybe 30% of the time?) he acts pretty lethargic. He also had a poop earlier today that he looked like he was having trouble passing, like he was constipated, and one of his front fins is split up its center. I'm considering moving him into the hospital tank, which is still dosed with salt, but what if there really was some kind of water parameter problem with that tank that made the dead guppy worse? The water came directly from my 20 gallon tank straight into the hospital tank, and my readings all seemed good and were taken right before I set up the hospital tank (I will put the numbers at the bottom in case you're interested).
I ordered the trio of medications that Aquarium Co-Op recommends (first-time customer; thanks, Aquarium Co-Op!). My main question is: Can I / should I dose the whole 20 gallon tank with the three meds when they arrive? But if I do... will it hurt the shrimp? Alternatively, should I move the weaker guppy into the hospital tank and dose just that tank? OR, should I just leave the weaker one be for now and give him a chance to rest without me bothering him?
Water parameters:
ph = 7.4 - 7.6
Ammonia = 0 - 0.25
Nitrite = 0
Nitrate = 0
kh = 3 degrees / 53.7
gh = 7 degrees / 125.3
Calcium = 40