I HAVE A 500 gallon pond how many koi can I put and its 1 and half to 2 feet?

For a 500-gallon pond, a general rule of thumb is to allow about 1 koi fish for every 100 gallons of water. This means you could comfortably keep around 5 koi fish in your pond. However, since koi can grow large (up to 2 feet or more), it's important to consider their adult size and the potential for overcrowding, so starting with 3-4 koi might be a safer option. Make sure to also factor in proper filtration and aeration for their health.