Click to Skip Ahead
A Black Moor Goldfish or two can be a stunning addition to any fish tank or aquarium. Their unusual velvety black coloring and elegant, good looks are sure to earn admiration from guests. They are unique and rewarding pets. Watching them can be soothing and relaxing, and looking after them is a fulfilling pastime.
If you have just acquired one or are thinking about it, you may wonder how big they will get and how best to accommodate your new fish. Read on to find out whether you can expect your Black Moor to carry on growing or whether it’s not likely to get any bigger.
Black Moor Goldfish Breed Overview
The Black Moor is a type of telescope goldfish, which is a member of the collective known as the fancy goldfish. Fancy goldfish have a double set of caudal fins compared to common goldfish with a simple single-finned tail. They are generally less energetic swimmers than single-finned goldfish. They do not exist in the wild but were developed in captivity in China between the 1400s and 1700s.
Black Moors are characterized by their large protruding eyes, black color, and beautiful flowing fins, which they inherited from the Fantail goldfish from which they are descended. A juvenile Black Moor resembles a bronze Fantail goldfish, as they only develop their black color as they mature.
Only true Black Moors retain the black color for their entire lives. Many black goldfish believed to be Black Moors fade to gray, white, or gold or become mottled, revealing their identity as normal telescopes. It is true, however, that Black Moors kept in warmer water may fade to a metallic orange. Black Moors may also fade with age.
The combination of the black color and protruding eyes results from a specific gene expression. Black Moors can produce normal offspring that are neither black nor exhibit the trademark protruding eyes.
Black Moor Goldfish Size and Growth Chart
On average, fancy goldfish are not as large as common goldfish, such as the Comet. Most fancy goldfish average around 6 to 8 inches long, which is true of the Black Moor.
The table below shows how you could expect your Black Moor to grow from hatching to adulthood.
| Age | Length Range |
| 1 week | 0.2–0.5 inches |
| 4 weeks | 0.5–1 inches |
| 8 weeks | 1–1.5 inches |
| 3 months | 1.8–2.3 inches |
| 6 months | 2.9–3.2 inches |
| 9 months | 3–4 inches |
| 12 months | 3.5–5 inches |
| 18 months | 6–6.5 inches |
| 3 years | 7–7.5 inches |
| 6 years | 7.5–8 inches |
A Black Moor that is kept under optimal conditions (which we will discuss later on) is expected to max out at between 4 and 8 inches in length. Of course, there are always outliers and anomalies. There are many reports of Black Moors reaching 10 inches.
The previous growth rates are an example, and the actual growth trajectory can vary greatly depending on the Black Moor’s living conditions. The factor exerting the greatest influence on the growth rate will be whether the fish are indoor or outdoor pets. Outdoor fish’s growth rate will be affected by cooler water temperatures in winter; however, their final adult size will ultimately be unaffected.
When Does a Black Moor Goldfish Stop Growing?
A Black Moor grows most in its first year of life, with the most significant size increases in the first few weeks. When your Black Moor reaches the 2-year-old mark, it will have achieved its approximate adult size.
This is approximate because goldfish are indeterminate growers, meaning if the conditions allow, they can continue to grow for their entire lives, albeit very slowly. Most Black Moor owners notice that their fish don’t continue to grow beyond around 6 years of age.
Black Moors live for 10 to 15 years if well-cared for, but reports of fish living to 20 years are not uncommon.
Factors Affecting the Size of Black Moor Goldfish
Several factors affect how fast and when a Black Moor grows and its ultimate adult size.
- Tank Size: A Black Moor requires a 20-gallon tank with an extra 10 gallons for each additional fish. A smaller tank may stunt their growth, as will overcrowding.
- Water Conditions: Their water needs to be kept in an optimal range of temperature and pH, with careful attention paid to oxygen and ammonia levels. The water must be regularly cleaned and replaced.
- Nutrition: Black Moors must receive a nutritionally balanced diet of the correct food to grow optimally. An incorrect diet can result in poor health or death. Too little or too much food can result in stunted growth or obesity, respectively.
- Genetics: A Black Moor’s size is primarily predetermined by its genetic makeup. If a fish is descended from a line of small goldfish, it will most likely also be a small fish, and vice versa.
Ideal Diet for Maintaining a Healthy Weight
Black Moors should be fed a good-quality goldfish pellet, preferably one that sinks, as they like digging for food. Due to their telescopic eyes, they may struggle to see food that floats.
They are omnivorous and enjoy plant foods such as broccoli, algae, spinach, shredded lettuce, and cucumbers, as well as freeze-dried animal foods such as bloodworms, daphnia, and brine shrimp. However, they should not eat fresh animal foods since they may contain harmful parasites.
How to Measure Your Black Moor Goldfish
Aquarists measure their fish in various ways and should stipulate which measurement they have used.
- Tip of the nose to the tip of the caudal fin (tail)
- Tip of the nose to the V in the tail
- Tip of the nose to the end of the caudal peduncle (this is where the tail joins the body)
Unless otherwise stated, the first measurement is the most commonly used. Whichever measurement you decide to use, make sure that you use it consistently when recording your Black Moor’s growth over time.
Measuring your Black Moor should be done quickly and efficiently so that your fish is out of the water for as short a time as possible. Have a tape measure or ruler, gently remove your fish from the water, and place it flat on its side in your hand. It is best to do this over your fish’s aquarium in case it wriggles and jumps out of your hand. Quickly line up the ruler next to your fish and record the measurement of your choice.
Conclusion
Under the right conditions, your Black Moor goldfish can grow 6 to 8 inches long. The time your fish takes to reach this size may vary depending on its tank size, water conditions, feeding regime, and tank mates. Don’t forget to factor in genetics. If your fish isn’t getting bigger despite optimal conditions, don’t be tempted to overfeed it since it may have reached its maximum genetic potential.
Featured Image Credit: Darren Eldridge, Shutterstock
