Is epoxy toxic to fish? That is a very valid question, is it not? There are a couple of things you need to keep in mind when trying to decipher this, especially if you’re building a water feature that is going to house fish.
First remember that generally, epoxies that can be purchased at local hardware stores may indeed be toxic to fish. This is because these types of epoxies have a very specific purpose intended for them and that purpose does not revolve around housing aquatic life.
Epoxy coatings can leach off toxins both before they are cured and after they are cured. For purposes of housing fish, it’s this time afterwards that is most important. You will have applied the epoxy and let it cure before filling you pond back up and if the epoxy leaches toxins off after the cure, then your fish are in danger.
So how do you know if the epoxy is toxic or not? Well the easiest way is to read the epoxy technical data sheet and the MSDS (material safety data sheet) provided by the manufacturer. These two documents, along with a chat from a representative of the company can help clarify that.
The MSDS sheet will contain general information about the epoxy, including handling information. The technical data sheet will have scores of information in it regarding the coating you will find test data that covers anything from strength properties to, yes you guessed it, toxicology testing.
So do not be afraid to ask for these documents. You might be amazed at what you can learn.