Gold Barb With Reddening

[DaveA76]

hi ive noticed today that 2 of my 5 gold barbs have a reddening from thier bellys to thier anal fin on the lowerer half of thier bodies its not bright red just like a red tint and 1 of them seems to have the same reddening to its dorsal fin they are not bloated or showing any signs of illness and are still shoaling and eating well, is this normal ?
i havent got any water stats as my test kit has run out and get a new one tomorrow for fathers day