i have a 12in,1 year old red dragon male,i did a water change a week ago like i do every 2 weeks 50%,sence then he has been staying at top of the tank hiding behind a plant and he used to be very active.his color is good,he is eating everyday -hikari bio gold-.he is in a 125. his tankmates are 4 redpoints 2 firemouths and a female flowerhorn all acting fine, and all get along. i have not tested the water. the last water change i did totally rearrange the tank. do you think that this is any thing to worry about?