Fish

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.

Bettas are insectivores, not community fish. The pellet standard, frozen and live foods, portion sizes, safe emergency substitutes and the foods that cause bloat.

A goldfish lives 10 to 15 years and outgrows every bowl it is sold with. Real lifespan, adult size, tank volume, feeding and the behavior behind that stare.

Fancy goldfish reach 6 to 8 inches and live 10 to 15 years. Which varieties are hardy, what tank two of them need, and what actually kills them.

Black mollies reach 3 to 4 inches and live 3 to 5 years in hard, alkaline water. Group size, tank mates, fry counts and the shimmy problem.