Goldfish
Overview
A classic ornamental fish that comes in many varieties and colors.
Origin: China
Family: Cyprinidae
Physical Characteristics
Habitat Requirements
Care and Feeding
Diet Information Goldfish are omnivores with a preference for a more plant-based diet. Their digestive systems are different from many other fish, lacking a true stomach. This means they need food that is easily digestible and high in carbohydrates, not just protein. Staple Diet: High-quality sinking pellets formulated specifically for goldfish are the best option. Sinking pellets prevent the fish from gulping air at the surface, which can lead to buoyancy issues and swim bladder problems, especially in fancy varieties. Vegetable Supplement: A crucial part of a goldfish's diet is plant matter. You should regularly feed them blanched and shelled green peas (a great remedy for constipation), blanched spinach, or lettuce. Occasional Treats: You can offer occasional treats like bloodworms, brine shrimp, or daphnia, but these should be fed sparingly as they are high in protein. Avoid Overfeeding: Goldfish are notorious for being "beggars" and will always act hungry. Overfeeding is a leading cause of water quality issues and health problems. Feed a small amount that they can consume in 1-2 minutes, 2-3 times a day.
Breeding
Breeding Difficulty: Moderate
Breeding Notes: Spawning Triggers: Spawning is typically triggered by a combination of a natural or simulated change in seasons. Temperature Change: A gradual increase in temperature after a cooler period (e.g., in the spring) is a key trigger. Water Changes: Large, cool water changes can also simulate a heavy rainfall, which often triggers spawning. Identifying Sex: Males: During breeding season, males develop small, white bumps called "breeding tubercles" on their gill covers and pectoral fins. They will also chase and nudge the female's abdomen. Females: A female ready to spawn will become noticeably plumper and have a swollen abdomen as she fills with eggs. Spawning Process: Spawning is a high-energy, often chaotic event. The male will chase the female, nudging her to release her eggs, which are then fertilized by the male's milt. They are "egg scatterers," and the eggs are sticky, adhering to plants, spawning mops, or the tank decor. Parent Removal: Once spawning is complete, it is essential to remove the adult fish from the tank. Goldfish will quickly eat their own eggs and fry. Hatching & Fry Care: Eggs hatch in about 2-7 days, depending on the temperature. Healthy eggs are translucent, while infertile or fungused eggs will turn white. The fry are tiny and will need to be fed "infusoria" or "liquid fry food" for the first few days. Once they are free-swimming, they can be transitioned to newly hatched baby brine shrimp or finely crushed pellets. Culling: A major part of breeding goldfish is culling, or the selective removal of fish with deformities or undesirable traits. This is necessary to maintain a healthy stock and to prevent overpopulation, as a single female can lay hundreds or even thousands of eggs.
Compatibility
Peaceful
Compatibility Notes Goldfish are generally peaceful but can be a danger to smaller fish due to their size and tendency to put anything in their mouths. They also have a very high "bioload" (they produce a lot of waste), which can quickly foul the water for other species. The main compatibility challenge, however, is their need for cool water. Best Tank Mates: Other goldfish are always the best choice. However, it's important to match breeds. Slim-bodied/single-tailed goldfish (Common, Comet, Shubunkin) are fast swimmers and should be kept together. Fancy goldfish (Oranda, Ryukin, Ranchu, Fantail) are much slower and often have impaired vision. They should be kept with other fancy varieties to ensure they can get enough food and aren't outcompeted or bullied. Other Potential Tank Mates: Hillstream Loaches: These fish are adapted to cool, fast-flowing water and are great at cleaning up algae. Dojo Loaches (Weather Loaches): A popular and peaceful bottom-dweller that enjoys cooler temperatures. White Cloud Mountain Minnows: These are small but fast fish that can tolerate the same cooler water temperatures as goldfish. Fish to Avoid: Tropical Fish: Most tropical fish require much warmer temperatures (75-80°F+) than goldfish, which thrive in cooler water (65-72°F). Keeping them together will stress both types of fish. This includes popular species like Bettas, Tetras, Guppies, and most Cichlids. Small Fish: Any fish small enough to fit into a goldfish's mouth will eventually be eaten. Fin Nippers: Fish that are known to nip fins, such as some Barbs, will harass the long, flowing fins of fancy goldfish.