my brother has been using my net for his pond.and i used it in my tank a couple times.now i have some little white bacterial things.its not planaria.and i also have some micro slug looking things on my wall with the white bacterial thingg.they are all over the wall and there are alot.are these things harmful for my fish.if any one knows what these things are please help.

not sure what they are but I would add some salt to your tank, that might help.

I would do more frequent water change & add some salt.

a picture will help. It will give us more accurate description.

Do a 50% w/c and add 5 table spoons per gal of salt and raise temp at 80