Q&A for How to Tell if Your Goldfish Is a Male or Female

Goldfish breed in the spring and need the temperature to be adjusted. First, lower aquarium temperature to 52°F (11°C). Then, when you are ready to breed them, raise the temperature 3°F (1.7°C) per day until it reaches 72°F (22°C).

Sadly, the average household goldfish lives about six months because no one does the research on how to help them live longer. Goldfish can actually live up to 20 years and almost every species can grow over 6 inches (15cm). Goldfish can't live in goldfish bowls because it doesn't allow them sufficient room to grow. It also doesn't allow for decorations to be added, and goldfish are prone to depression because they are very curious fish and when there is nothing to enjoy, they'll pine. Always make sure your goldfish has enough room to swim. Compare it to yourself, would you like to live in a bowl the size of your bed? Also, there are different types of goldfish and the more streamlined bodied ones shouldn't be put with rounded bodied ones because they swim faster and will eat all the food.

If it is nipping the tails of the others, then this is not a act of breeding, and it could be either. But if he swims under the others and noses their bellies, this is a sign of a male fish during breeding season.

You can remove as much dirty water as necessary out of the tank using a cup and a bailing method rather than a suction hose and replace it with clean water. Upsetting the bottom of the tank where they will be releasing their eggs can interrupt their spawning and will fail to fertilize their eggs. When adding fresh water, make sure it does not disturb bottom by pouring the water slowly through a colander or strainer, or against the side of the tank.

This is most likely aggressive, bullying behavior and it's probably best to separate the fish before one of them kills the other.

Yes, so if you spot goldfish eggs on plants or decor, take either the goldfish or the eggs out. Put the eggs in a hatchling tank. Baby goldfish may also need oxygen to help them.

It all depends on how you take care of your fish. Common and Comet goldfish need more room than any other species, but generally females live longer, as males don't have a grand purpose. Females need more time so they can pass on more generations, as males just need to mate with them.

It could be a swim bladder disorder. My pop-eyed goldfish got this and died a few weeks afterwards. This is caused by swelling of the intestines. You should feed it peas instead of flake food so that it won't get air in its stomach.

It could be either gender. Look at the anus size; females have a large anus, whereas males don't. Males will also chase females.

Not usually. Goldfish are friendly fish. If your goldfish do fight, you should put a divider in the tank, separating the two fish.

Goldfish do not get pregnant. The females lay eggs and the males fertilize them.

More than 300 breeds.

Yes. They resemble the fish's natural food, so it's done instinctively.

If it only lived 8 to 9 months, no. A wild goldfish will live up to 30 years. The average lifespan for a well-cared-for goldfish is closer to 10 years.

Goldfish breeding usually begins in early March, but if you are inconsistent with goldfish feeding it could alter their breeding periods.

Specific coloration isn't assigned to either sex. You could have an extremely colorful female and a solid color male, or vice versa.

Usually not, because the goldfish may eat the tadpoles, and if the tadpoles are wild caught they may transfer diseases to your goldfish.

Yes, because it needs someone to help lay her eggs, or it could be a fight between them. The male may go after her eggs and she wouldn't like that. It could even be to tell the male she needs help.

It's probably just genetics. Some are bigger than others, just like humans. However, my "runt" goldfish didn't seem to grow like all the rest, and then one week he just grew and grew out of nowhere, and now he's bigger than a few others. Some are just slow starters.

No. That would be like you living in your bed. Also, they need a filter and a lot more. If you keep them in a bag they will die within a week.

It might be a male, and he might be ready for breeding season. If your fish always had this spot, then it might be part of his or her coloration.

If they're also swimming at the walls it could mean that they feel cramped in the space and they need a bigger tank.

All goldfish are the same species, similar to dogs. They just have been selectively bred to show different traits. Thus, yes, two different types can breed.

Some goldfish will, some won't. It really comes down to the individual fish.

No, usually the females are bigger, but it also does depends on the shape of their body and their behaviors.

That depends on which breed of goldfish you are trying to use. About 18 months old is usually a healthy age for your general goldfish breed, and the size of different fish can vary temendously based on environment, breed, diet, etc.

You should feed your goldfish small amounts 2-3 times a day.

Make sure the tank has a clean way of filtering and a good source of oxygen, feed them regularly but do not overfeed. Normally I add a cleaner fish to keep the tank cleaner and some plants for extra oxygen. There's a whole article here you might find useful: Care for a Fantail Goldfish .

Eggs are very tiny. They are pretty easy to spot, though, just look for tiny white balls in your tank. There are usually a lot of them.

If you restrict protein-rich foods like brine shrimp and lower the temperature of the water for a couple of weeks. Slowly raise the temperature back up to room temperature or slightly warmer. Then reintroduce the brine shrimp. Warm water and live/frozen foods will simulate the spring encouraging them to breed. There is more to it than that, but that is basically what you need to do.