Got a horse issue

[funkejj]

Came home tonight to find one horse swimming around and another hiding. Went to feed and one ate well and couldn't find the other. Ten minutes goes by and the second horse comes out then goes nose first to the bottom of the tank and stays there. My wife freaks out and immediately thinks he is dead. I nudge him with the baster I use to feed and he gets up slow and swims then again back to the bottom of the tank. His tail appears more white towards the tip of it. I am open to any ideas.

 

[funkejj]

Here is a pic of the tail.

 

[rayjay]

Most likely a strain of vibriosis due to water quality. May be some deposits of food trapped somewhere or just general accumulation of organics in the water.
Treatment is in a hospital tank with temperature dropped to 68° (no more than 4° per day drop).
Watch for eating patterns as the medication often takes away their desire to eat.

 

[funkejj]

My water parameters are near perfect. Nitrates are 5 phosphates are non existent. Temp is at 72 degrees. Salinity is 1.024 ph 8.1. We will remove him to a hospital tank and treat him with antibiotics.

 

[rayjay]

Unfortunately many people think their water quality is near perfect when their hobby test kits are reading what they should.
However, there are so many other problems that can be in the water and there are no test kits for and bacteria beds producing strains like vibriosis cannot be detected.
The white tail is indicative of a bacterial infestation that is usually a vibrio type and is treated in a hospital tank with Furan II. (sorry I forgot to mention the name of the medication in my previous post)
By having the lower temperature, it makes the spread of the bacteria slow up allowing for recovery when treated.