Maximum size : 10 cm

European Bitterling - Rhodeus amarus : Complete Fish Profile & Care Guide

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European Bitterlings (Rhodeus amarus) are a fascinating addition to any coldwater aquarium or pond due to their unique appearance and peaceful demeanour. These fish are incredibly adaptable to various water conditions, making them an excellent choice for beginners and experienced fishkeepers alike. Not only are they easy to care for, but European Bitterlings also make great tankmates with various species, making them a great addition to any community tank. Their non-aggressive nature ensures that they won't bother other fish or nip at their fins.

An appropriate habitat for bitterling fish should encompass a pond with a minimum capacity of 1000 liters to accommodate a group of four individuals. For each additional bitterling added to the group, an extra 250 liters should be allotted. To facilitate overwintering in regions with cold winters, the pond's depth should range from 1 to 1.30 meters, ensuring that freezing does not extend to the bottom. Employing an ice freezer can aid in maintaining vital oxygen exchange during the colder months by preventing complete surface freezing.

Bitterlings thrive in environments characterized by gentle to nonexistent water currents and abundant aquatic vegetation. Ideally, the pond's substrate should consist of sandy or muddy terrain. A shallow water zone, extending up to 20-40 cm in depth and generously adorned with aquatic plants, serves as an ideal habitat for both bitterlings and mussels. The substrate in this region should consist of fine sand, creating an optimal setting to observe the intricate interactions between the small runners and the mussels with which they share a symbiotic relationship.

These fish have an eye-catching appearance, with a laterally compressed body with a beautiful bluish-green iridescent sheen and striking rose-coloured dorsal and anal fins. The white pelvic and pectoral fins contrast perfectly against their vivid blue-green stripe and whitish-to-reddish belly. During the breeding season, the males of this species transform, developing a brilliant orange belly and bright red fins. This change adds an exciting and vibrant element to any aquarium or pond. With their striking appearance and peaceful nature, European Bitterlings are a fantastic choice for any aquarist looking to add a unique and colourful touch to their collection.

European Bitterling Photos

Sexual Dimorphism

Distinguishing between male and female European Bitterlings can be arduous, particularly when not in breeding conditions. However, when these fish are ready to breed, there are evident differences between the sexes. For instance, males exhibit a remarkable increase in vibrancy, and their behaviour shifts significantly. Conversely, while females' colouration remains unchanged, they develop an ovipositor.

Quick Facts

Scientific NameRhodeus amarus
Year Described1782
Other NamesNone
OriginsFrance , Russia
Max Size10 cm
Aquarium LevelBottom - Middle
DifficultyBeginner - Intermediate
Best kept asGroups 8+
Diet & FeedingOmnivore
ReproductionEgg Depositor
LifespanUp to 5 Years

Water Parameters

Water TypeFreshwater
pH 7.0 - 7.5
GH 0 - 6
TDS 100 - 200
Ideal Temperature
55 - 71
12 - 21

Natural Habitat

Rewritten: The European Bitterlings are a fascinating fish species endemic to central and eastern Europe and northern Asia. These fish can be found in a range that stretches from the Rhone River basin in France to the Neva River in Russia, but interestingly enough, they are absent from Denmark, Scandinavia, and significant parts of the United Kingdom.

In their natural habitats, European Bitterlings reside in shallow, clear, and stony waters that are still or slow-flowing. These fish can thrive in a variety of aquatic environments, including ponds, streams, lakes, canals, rivers, backwaters, and oxbows. The fish prefer to live in densely vegetated habitats with mud or sand substrate and areas with mussel populations.

Despite their abundance and expansion in most of their range, European Bitterlings face a significant threat in some areas due to weed clearing, water pollution, and stocking of predatory fish. These issues have resulted in a decline in mussel populations, ultimately leading to a decline in the European Bitterling species.


European Bitterlings display a fascinating and unique breeding method that occurs between April and June when the fish reach sexual maturity at around one year old. During the breeding season, males will develop an orange belly and reddish fins, while females produce a long, tubular ovipositor. To reproduce, females insert their ovipositor into the incurrent respiratory siphon of a freshwater mussel or clam and deposit their eggs in the mollusc's gill chamber. Females can release anywhere from 1 to 6 eggs, with each spawning.

The eggs are fertilized by the male's sperm and ingested by the mollusc into the gill chamber, along with water for respiration. The eggs will remain inside the mussel's gill cavity for approximately four weeks until the fry emerges, fully capable of taking care of themselves and leaving the host. Interestingly, the breeding periods of the fish and mollusc coincide, and the mollusc, in return, releases its larvae onto the bitterling, where they develop in the skin of the fish.

Diet & feeding

European Bitterlings have a varied diet in the wild, consisting of algae, insects, crustaceans, and organic and inorganic matter. When kept in an aquarium, they are generally not finicky eaters and will accept most types of food. However, to provide a well-rounded diet, it is recommended to offer a combination of dried foods such as flakes, pellets, and granules, along with live and frozen foods such as bloodworm, daphnia, and brine shrimp. This will ensure that they receive all the necessary nutrients to maintain their health and vitality.

Frequently asked questions

European Bitterlings are peaceful freshwater carplike fish belonging to the Family Cyprinidae and the Genus Rhodeus. They are known as Bitterlings for their distinct bitter taste.

European Bitterlings can grow to anything from 6 cm up to 10 cm in size.

European Bitterlings are unfussy and will pretty much eat anything you give them. A mixture of dried food such as flakes and pellets as well as live and frozen foods such as daphnia, brine shrimp or bloodworm are all suitable for your fish.

European Bitterlings are hardy, adaptable fish that you can keep in ponds and aquariums; therefore, you can keep these fish with various species, including Goldfish, Danios and Minnows, as well as coldwater natives such as Murray River Rainbows. \r\n

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