Hi again all,got home from work and my BTA does not look well at all, he is all curled up, he recently relocated to a darker spot under some rocks, and I am struggling to get food to him , but he looks quite ill,pulled his feelers/what ever right in and the look like pieces of string

water conditions
salinity 1.25
PH 8.0
Alk normal
Nitrite 0.2 ppm
Nitrates 15 ppm
Temp 25 celcius