Yes. Ich is not always going to show white salt-like spots on the fish’s body, especially if the fish are resistant or immune to it. But as Long as there is a host fish in the tank, there will be ich if it’s introduced into the system earlier or later on either a carrier fish and/or anything wet that has an irregular surface area for their cysts to latch onto and lay dormant like coral frags, clean-up crew etc.
Honestly it’s hard to completely avoid, which is why most people just adopt the “feed them well and have a stress-free environment/stable water parameters etc” policy. The fish can fight things like that off, but not so much things that are more deadly like velvet(and very similar but much more lethal).
Generally it’s unlikely you’ll bring in these parasites into your system via other things than infected fish though, but there’s still a chance. Sent from Singapore Reef Club mobile app