Can anyone tell me what might be wrong with this fish

Hi there, this Gold White Cloud Minnow has been staying in this one area of the tank since yesterday. It just swims and floats here. It appears that its tail sinks down and the fish will drift, then it will swim. No other fish (13 other minnows and Tetras) haven't been interacting with it, its not schooling with them like normal. This fish has always been the runt, but it looks skinny to me now. I put dried bloodworms in there earlier this evening and it was still interested in eating. But it is definitely not acting normal.

I've had this fish since August. I changed the water today, so my water column has floating particles in it. It normally doesn't look this bad.
Tank Size - 60 gallon, planted
Ammonia - 0
Nitrite - 0
Nitrate - 20
PH - 7.4

Can anyone help me figure out what is happening please?


Video on YouTube

 

Hi there, this Gold White Cloud Minnow has been staying in this one area of the tank since yesterday. It just swims and floats here. It appears that its tail sinks down and the fish will drift, then it will swim. No other fish (13 other minnows and Tetras) haven't been interacting with it, its not schooling with them like normal. This fish has always been the runt, but it looks skinny to me now. I put dried bloodworms in there earlier this evening and it was still interested in eating. But it is definitely not acting normal.

I've had this fish since August. I changed the water today, so my water column has floating particles in it. It normally doesn't look this bad.
Tank Size - 60 gallon, planted
Ammonia - 0
Nitrite - 0
Nitrate - 20
PH - 7.4

Can anyone help me figure out what is happening please?


Video on YouTube

It's only one fish that's affected so I may be wrong but... This is the time of year, at least in the US, that municipalities clear the pipes and overdose the chlorine, often without saying anything. So it's possible that there's chlorine in the tank, especially if it happened immediately after a water change. This can be fixed by adding more dechlorinator. Again, I may be wrong.

 

Thank you for replying. I use R/O water, and test for chlorine and its at zero.

 

Thank you for replying. I use R/O water, and test for chlorine and its at zero.

If it's always been the runt, perhaps bad genes? Failure to thrive? I wouldn't say parasites or anything communicable unless you added a new fish recently.

 

No new fish in about 4 months. I am thinking you are right about the failure to thrive. Originally when I got this one and the other minnows, they were all similar size. This one was slow to grow. Now they others are way bigger than this one. Thank you for your help.