1. Animal species
This guide applies to the following families of freshwater fish and is considered a basic aquarium keeping guide. For the families mentioned, there are representatives who are suitable for this, while others make significantly greater demands on the care. The dealer can advise on suitable species for the current aquarium. The respective families are: Carpelax (Characidae ) , Spawning tooth carp (Poecilidae), Egg-laying tooth carp ( Notobranchiidae ), Gouramis (Osphronemidae), Carps ( Cyprinidae ), Cichlids ( Cichlidae ), Rainbow fish ( Melanotaeniidae ), Goats ( Gobiidae ), Badis ( Badidae) ), Axefish ( Gasteropelecidae ), Catfish ( Loricariidae ), Banjo catfish ( Aspredinidae ), Thorn catfish ( Doradidae ), Armored catfish ( Callichthyidae ) and Smellings ( Cobitidae ). The list is not exhaustive.
2. Full grown size
It is a common misconception that fish adjust their growth according to the size of the aquarium. Always consider the maximum size of the fish when choosing fish for the aquarium. Be aware that some available freshwater fish reach a size unsuitable for most aquarists. This guide is limited to fish that reach a maximum size of 30 cm.
3. Life expectancy
In general, you should expect a lifespan of at least 2-8 years, depending on the species. However, there are many fish that reach a higher age.
4. Recommended size and layout of facility or cage
The size of the aquarium must allow the fish to have the opportunity to swim freely. It provides good well-being and makes watching the fish exciting. There should be at least 2 liters of water per cm fish, for fish up to 15 cm. For larger species there should be a minimum of 4 liters of water per cm fish. In addition, the aquarium should be at least 6 times as long as the total length of the fish. It must always be assessed individually for the aquarium in question. For most aquariums, approx. 4 cm of cleaned aquarium gravel or sand is suitable as a base layer. Aquatic plants, stones and roots are placed here, which primarily function as visual barriers and hiding places for the fish. Plants also have a positive effect on water quality.
5. Special care needs, including special requirements for temperature conditions The water temperature is kept stable with a thermostatically controlled heater. Many tropical aquarium fish thrive at 24-27 °C, but always pay attention to the needs of the species in question. Use a thermometer to check the water temperature daily. The quality of the water is crucial for the well-being of the fish, and can be maintained with the help of a filter. The filter must be adapted to the size of the aquarium and work around the clock. It is important that the outlet from the filter breaks the surface of the aquarium so that oxygen is constantly supplied to the water. Once the aquarium is set up, you should wait a few weeks before the first fish move in. This period allows the aquarium water to stabilize and allows the aquarist to make adjustments without affecting the fish. In addition, the biological filter, which is important for water quality, will gradually build up on all surfaces of the aquarium. Always add only a few fish at a time to both new and established aquariums. This gives the aquarium's biological activity the opportunity to adapt, so that there are no unwanted fluctuations in the water quality. After transport home, the fish must get used to the new aquarium. This is done by adding aquarium water to the transport water in a 1:1 ratio over a period of 30 minutes. Water changes are a necessity in order to remove the waste substances that accumulate in the water. Change 20% per week in a normally loaded aquarium. The bottom layer of the aquarium is cleaned every few months with a mud bell, while the aquarium decorations can be washed in clean water as needed. The filter is cleaned in water saved from the aquarium's water change. This avoids the biofilter having to be started again. To evaluate the water quality, a test kit is used, which is bought in the pet store. The most important waste substances to test for are: ammonium, nitrite and nitrate. Water changes can then be adjusted according to the test results. The circadian rhythm is kept stable with 10-12 hours of artificial light daily.
As a starting point, use the same type of feed that the fish are used to at the dealer. Many fish are sensitive to sudden changes in their feed, and any change should be made gradually. They are fed twice a day with an amount that can be eaten within a few minutes. Flake feed and granules adapted to the individual species are recommended as main feed if possible, while thawed frozen feed such as mosquito larvae are used as supplements.
7. Social needs
Some fish thrive best in the safety of a shoal, while others are solitary. A deviation from their natural needs can be a major stress factor resulting in illness. Ask the dealer about the suitability of the individual species for the current aquarium.
8. Propagation, brood care and possible neutralization
Many freshwater fish breed frequently in the aquarium, typically after a water change. To be successful in breeding, it may be necessary to isolate breeding fish or their offspring. Be aware that baby fish require more frequent feedings, which affects water quality.
9. Typical signs of illness and reduced well-being
Disease is most often caused by unsatisfactory water quality. If the fish loses its appetite, has cloudy eyes, swims irregularly or has atypical spots on its body, this may be a sign of illness. Review the aquarium's installations and test the water for waste substances. Carry out water changes and ask the pet dealer or a vet.
Any other information
Suggested fish suitable for basic aquarium keeping: Guppy (Poecilia reticulata), Platy (Xiphophorus maculates), Butterfly cichlid (Papillochromis remirezi), Armor catfish (Corydoras sp.), Kribensis cichlid ( Pelvicachromis pulcher), Ancistrus catfish (Ancistrus sp.)
Guidance on large freshwater aquarium fish
This guide is an addendum to "Care instructions for aquarium fish in freshwater" and cannot stand alone. In the general aquarium trade, there are a number of species that can grow very large. These fish are only suitable for private aquarists under special circumstances. It must be emphasized that fish do NOT adapt their size to the aquarium, but will grow to average size with proper care! Therefore, you should never acquire fish that you cannot house for the entire life of the fish. It can be very difficult to dispose of large aquarium fish, and only in very rare cases can pet shops or public aquariums accept them. The care is basically as described in "Care instructions for aquarium fish in fresh water", and many of the species mentioned in this supplement do not have special requirements for water type or water quality. The important thing in this context is to get the aquarium dimensioned correctly and get the aquarium's interior and technology to match the needs of the fish. The size of the aquarium must be dimensioned taking into account the size and activity level of the fish. It is recommended that the length of the aquarium is at least 6 times the length of the fish, while the width and height should be at least 2 times the length of the fish. Ready-made glass aquariums will often be insufficient, and here you must be prepared to have your aquarium custom-built. The arrangement must be robust so that roots or stones cannot topple over when the fish poke at them. Cover plates, light boxes and other things must be of solid quality, and the aquarium's technical installations must be thoroughly shielded. Fish measuring 50 cm or more eat large amounts of food, and even hardy fish can suffer from a high nutrient content in the aquarium. Therefore, great demands are placed on water changes, and a traditional aquarium filter will often be insufficient. Here, a filter that is dimensioned for garden ponds or similar is recommended. The following fish are examples of species where their size alone places special demands on the aquarist: Sucker catfish ( Hypostomus plecostomus, Pterygoplichthys pardalis ) Up to 60 cm Red tail catfish ( Phractocephalus hemioliopterus ) Up to 134 cm Pangasius catfish ( Pangasius sp. ) 100 -300 cm Giant gourami ( Osphronemus goramy ) Up to 70 cm Armored pike ( Lepisosteus sp. ) 100-300 cm Black pacu ( Colossoma macropomum ) Cichlid ( Cichla monoculus ) Up to 70 cm Clown knifefish ( Chitala chitala ) Up to 120 cm Giant snakehead fish ( Channa micropeltis ) Over 100-150 cm Freshwater stingrays ( Potamotrygon sp. ) 30-150 cm Tiger spade catfish ( Pseudoplatostoma sp. ) 100 cm African lungfish ( Protopterus annectens ) Up to 100 cm Arowanna ( Osteoglossum sp. and Sceleropages sp.) 50-90 cm
Guidance regarding aquarium fish in brackish water
This guide is an addendum to "Care instructions for aquarium fish in freshwater" and cannot stand alone. Brackish water fish are recommended only for aquarists who have experience with basic aquarium keeping. Brackish water is a type of water that occurs when rivers empty into the sea, so that fresh water is mixed with salt water. Fish adapted to this environment are called brackish water fish. This grouping of fish, across normal systematic division, is defined by their particular adaptation to living in this type of water. The name says nothing about the fish's other characteristics; including size, behaviour, food choices etc. The brackish water aquarium is basically looked after like the freshwater aquarium, but the water must be supplemented with a special aquarium salt. The dosage depends on which fish will be in the aquarium. The most used method to measure the salt content of water is to use a hydrometer. This indicates the ratio between the specific gravity of the aquarium water and the specific gravity of fresh water (SG). It is this term that is most often used when describing the preferences of a brackish water fish. Note that salt content in water can also be stated in parts per thousand (parts per thousand). Be careful not to confuse SG with salt per million when checking the salt content. Evaporated water will leave a higher salt concentration in the remaining aquarium water and it will be necessary to top up with fresh water. Water changes are made with brackish water that has been thoroughly mixed before addition. Be aware that many of the brackish water fish kept in fresh water as juveniles require a gradual transition to brackish or salt water as adults. To avoid osmotic shock in the fish, changes in the aquarium's salinity must always be made very slowly. The fish below are examples of species that are suitable for the brackish water aquarium:
Brachygobius nunus (Brachygobius nunus)
The bumblebee fish thrives well in a small species aquarium with lots of hiding places and relatively low water flow. Their special suction cup on the underside means that they spend a lot of time attached to the aquarium decorations. Bumblebees can be difficult to feed and in some cases will only accept live food.
Puffer fish (Fam. Tetraodontidae)
Puffer fish are particularly demanding aquarium fish that, due to their aggressive behavior, are rarely suitable for social aquariums. They make great demands on feeding, and therefore even greater demands on filtration and water changes. Pufferfish are generally sensitive to poor water quality and have species-specific requirements for their aquarium. Be aware that there are many species of puffer fish and they can be difficult to identify correctly. Few of them are suitable for brackish water, but what they all have in common is that they are only suitable for the serious aquarist.
Moonfish ( Monodactylus argenteus) and Argus (Scatofagus argus)
Moonfish and argus are fast-swimming schooling fish that require lots of space and water circulation. They are often seen in fresh water as juveniles, but must quickly adapt to brackish water to survive. As they age, they will require a more saline aquarium; adult fish thrive best with a minimum of 20 ‰ salt. Both are hardy fish, but their greedy nature will put even well-functioning filter systems to the test.
This care guide has been prepared by the Council regarding the keeping of special animals in collaboration with Thomas Stensgaard.
The care instructions contain general information about the care of an animal species/animal group.
Further information can be found in the library or on relevant websites. The professional content of the care guide has been approved by the Council regarding the keeping of special animals on 16.12.2013 in accordance with the executive order on commercial trade in animals.
You are also very welcome to stop by the shop for more talk about fish, or to comment on this blog post.