Apisto pale after water change a while back

[KyleKVK]

I have an apisto that has turned really pale after a water change. This was months ago, and he’s still fine, but still pale. Typically I monitor for nitrates and only do changes when they exceed a certain point which is why it’s been a while

 

Aside from a little bit of algae due to it being summer, my tank is doing fine. Why is my fish so pale? I should mention his tankmates are all doing just fine. It’s strictly a one fish problem. He’s also still eating. 

[Colu]

Stress can cause fish to lose colour or lliness what are your water parameters