Author: Lena Marsh

A koi pond needs 3 ft of depth, 1,000 gallons, and hourly filter turnover. Here is what that costs, how to keep the water clear, and what really preys on koi.

Wild bettas are small, brown, short finned, and nothing like the fish in the cup. What they cost, how big they get, and whether they really live in puddles.

What one koi fish actually costs, why show grade fish reach thousands, how much pond water each adult needs, and what takes koi from a backyard pond.

Tetra fish need a school of six or more to behave normally. Here is what they cost, which species suit beginners, and why some batches die in week one.

Every koi variety is a combination of five base colors. Here is how to read the Japanese names, which colors are genuinely rare, and why koi change color with age.

The common pleco hits 24 in and needs 125 gallons, but six loricariids stay under 5 in. Sizes, feeding, tank setup, and why releasing one is illegal.

The queen angelfish reaches 18 in, eats sponges, and needs a 180 gallon tank. What it costs, how to tell it from a blue angelfish, and why it is not reef safe.

Platies are 2 to 3 in livebearers that need 10 gallons, hard water and a 2:1 female to male ratio. They also breed faster than most beginners expect.

The French angelfish is a 15 in Caribbean reef fish that pairs for life and eats sponges. It shares a name with the freshwater angelfish and nothing else.

Goldfish live 10 to 15 years in a filtered tank and 20 to 30 in a pond. The record is 43 years. Here is what actually sets the limit.