Aquarium Substrate

by Jason
(Lancaster PA)

What is the best substrate for goldfish.

Some places say sand is good, others say it is bad. Some say small stones, others say big stones. I am not using live plants, I am not breeding.

I have 3 moors, 1 telescope, 1 "feeder", 1 that I can not remember and a pleco that's about 11ish inches.

Thank you for the help

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Grant's Reply

Hi Jason

Good question, and I can understand why you are confused as all the answers have an element of truth.

First sand. I don't recommend sand because it compacts over time and is hard to keep clean. Depending on type, sand can turn the water alkaline as it dissolves.

A very coarse silica based sand would be the only type of sand I would use in a Goldfish aquarium.

I define large stones as stones that cannot be picked up by the Goldfish when browsing for food.

The biggest problem with very big stones is food can fall into crevices that can't be reached by the fish, especially telescopic eyed fish.

Another danger with large stones is if the fish grow big enough so they become capable of picking them up. I lost a fish recently when it choked on a pebble.

Substrate with pebbles larger than 1/4" (6mm) is harder to plant with live plants.

Larger stones do allow more water circulation between them which lessens the risk of ammonia pockets.

I define small stones as stones that are small enough for the fish to be able to pick up in their mouths and spit out.

Small stones don't allow as much water circulation so need to be stirred up and cleaned regularly.

Eliminating sand as an option, substrate size depends on the size of your fish.

You can go either small or large, but either way you need to be aware of the problems with each option.

Whichever way you go, choose substrate that is smooth and hard. This makes it easier to clean, and it won't alter your water pH.

The color should be on the darker side if you don't want your fish to appear washed out as they adjust their color to their surroundings.

You will notice most professional Goldfish breeders and many experts don't use any substrate.

The main reason is cleanliness.

It is far easier to keep a bare aquarium clean when you are feeding heavily than one with substrate.