Hello,i have a 96ltr tank with a few plants,a rock,boat and a few little other things,the fish i have at the moment are 4 zebra danios,and 7 neon tetra's,i do approx a 20% water cahnge once a week,clean all the glass and ornamonts,but i am starting to notice that i am getting a lot of what looks like fur growth on the rock and boat,how can i get rid of this is there any fish you can buy to keep this down,any help appreciated