We actually asked my wife's OBGYN about this recently (my newest boy is just now 4 months old) and he said there's nothing related to the fish, water, etc to worry about.
+1 was a couple years ago but ob was way more concerned with our chinchilla than my 500g tank. Just said being stung by my rays would be bad(obviously) but said its VERY rare for any water illnesses to be picked up.