Assorted Telescope Goldfish

Assorted Telescope Goldfish make peaceful additions that won’t cause any problems for the rest of your fish. They are easy to keep healthy if the tank is clean and they are fed a good diet, making them suitable for beginners.  Adult size:  12 – 20 cm, minimum tank size 40 litres.

The telescope goldfish (Carassius auratus) is one of over 125 captive-bred varieties of the fantail goldfish. They are thought to originate from China, where they were first developed in the early 1700s. This unusual variety of fantail was once called the Dragon Eye goldfish or Dragonfish. However, in later years, the Japanese christened the fish Demekins, and that’s what telescope fish are still called today.

The Telescope Goldfish is known for its large, protruding eyes that are set on the end of long cone-like stalks, which are mounted on the sides of the fish’s head. In some cases, the stalks can extend to 2cm. In juvenile fish under six months of age, the eyes appear normal in size, and the telescope effect does not begin to fully emerge until the fish matures.

Behaviour

Fancy Goldfish need plenty of space. The minimum tank size is 40 litres, but the more space you provide, the more likely they are to stay healthy.  Avoid using glass bowls instead of standard aquariums. These are usually too small, especially when your fish reach maturity.  Aim to have 30 litres of water per fish because though they will group together sometimes, they also like swimming off on their own.

Tank Conditions

Goldfish are known to be messy feeders. Over time, therefore, the water can quickly become unhygienic, leading to potential health issues. It is important, therefore, to install a suitable filtration unit.

Add a layer of sand or gravel to the bottom of the tank but since Telescope Goldfish are known to be diggers make sure the substrate doesn’t have sharp edges.  Also, you’ll need to use plant weights to anchor any live plants that you include in your aquascape or they will be uprooted.

Telescopes and other types of fantail and fancy goldfish need plenty of clear swimming space in the aquarium. These fish are poor swimmers who will struggle to cope with too much obstruction and dense planting. Plants should be positioned toward the rear of the aquarium, and any overgrowth must be pruned back to prevent the fish from becoming trapped among the leaves.

All goldfish require cold water. This means that you should keep your tank away from any heat sources and keep it in a cool room. If you place them in water that is too warm for them it can cause lifelong damage to their nerves.  Ideally the water temperature should be between 10 – 24°C.

Compatibility

The ideal temperature range for these fish is low compared to the preferences of other popular aquarium species. This reduces the amount of options available to you.  You’re further restricted by their long fins. Fin-nippers (like Tiger Barbs) will target the double fins. As slow swimmers, Telescopes can’t escape from fish that bother them.  Small shoaling fish are good companions. You could try Zebra Danios, Neon Tetras, Mollies, Rosy Barbs, or White Cloud Mountain Minnows. Angelfish and Dwarf Gourami are some possible larger options.   If you do want bottom feeders, try Corydoras Catfish, Kuhli Loaches, or Otocinclus.  You can add some small invertebrates without risk of them being eaten. Examples include Cherry Shrimp, Ghost Shrimp, Amano Shrimp, Nerite Snails, or Mystery Snails.

Feeding

In their natural environment goldfish will feed on plants, small insects, algae and anything else they can get hold of; however the majority of their diet is vegetation (this provides them with plenty of fiber). Generally you can start by feeding your fancy goldfish pellets or flakes.  Fancy Goldfish can easily develop digestive problems because their organs are so compact in their bodies, so it is important to design a healthy diet. This is simple because they are omnivorous and will eat most aquarium foods.  Try to supply some plant matter too, as this contains fiber which helps the digestive system. Green vegetables are good for this such as lettuce, spinach and marrow (zucchini).

Care

They are reasonably hardy, but they can quite delicate and may need a little more attention than other species. Their telescope eyes are an obvious weakness. Since their eyes are so large, but their eyesight is so poor, they can easily swim into sharp objects that could cause injuries.

They have a tough round body, but fragile eyes which can be damaged when being caught in a net. So you should make sure to place them in a tank with smooth objects and handle them carefully.

With all their organs squashed up in their small body, this can increase the likelihood of disease.

Swim bladder is a common problem and symptoms of this are obvious – the fish will either be floating on the surface or sitting at the bottom of the tank, since they can’t control their buoyancy effectively. Avoid feeding for 24 hours, then start to introduce fibrous foods such as vegetables.

Skin diseases, such as velvet disease are common for fancy Goldfish and are caused by parasites or bacteria. Symptoms will vary depending on the disease, but spots or color changes are typical.

Goldfish can also tolerate a slightly brackish environment, provided that salinity is kept below 10%.  This will help prevent many fungal and skin diseases.

See Fish Diseases and Diagnoses for help with diagnosing and treating diseases.

Providing the tank is kept clean, problems should be infrequent. This includes weekly water changes of 30% to maintain clean water.