No moth balls, they are toxic...and smell awful.
I understand there are deterrents like fox urine to apply around the areas they like to travel. Haven't personally used it though.
Also if you leave food out for dogs or cats it is a magnet. I almost had the little buggars in my arms they came so close, they got into my sun room more than once and had to be very cautious not put food out for the stray cat except a small amount in the morning, and had to close off the cat door I had in the window. More than one sad story of the raccoons eating expensive sushi in a pond. I have a 120 gal pond preformed and keep netting on it and so far the birds and raccoons haven't got any.
I took dark netting and strung black outdoor grade (for hiking and camping stuff) elastic from the sewing store woven through the 2 in spaces and cinched it up and pulled around and fits under the edges. It isn't as Zen looking but we have lots of predator birds. Also set a rock or fake rock cover so the fish can hide away if a raccoon or birds come maybe lose less that way. Also deterrent for some birds is having trees or over hang so they can't as easily swoop down and grab and go. I am thinking of adding a wood pergola over top extra shade for hot summer.
