There are goldfish outside in a huge iron bowl and the water is rusty so what can you use to seal from rusting that not toxic fish?

Here are a few non-toxic options that you can use to seal the iron bowl and prevent it from rusting, ensuring the safety of your goldfish:

1. Food-Grade Epoxy Resin: This is a non-toxic, water-resistant sealant that is commonly used in aquariums and other water features. It forms a protective layer that prevents water from coming into contact with the metal, effectively preventing rust.

2. Rust-Oleum Universal Spray: Rust-Oleum offers a variety of non-toxic spray paints that are specifically designed to prevent rust. These sprays create a durable coating that protects the metal from moisture and oxidation.

3. Polyurethane Sealer: Polyurethane sealers are commonly used for sealing decks and other outdoor surfaces. They are water-resistant and provide a tough, protective layer against the elements.

4. Porcelain Enamel Coating: Porcelain enamel is a non-toxic, durable coating that is applied by heating glass powder at a high temperature. This coating is highly resistant to rust, corrosion, and abrasion, making it ideal for sealing metal surfaces.

Before applying any of these sealants, ensure the iron bowl is clean and free of any dirt, debris, or loose rust. Follow the instructions provided by the manufacturer carefully to ensure proper application and curing.