Physical Characteristics
The common bream has an unmistakable appearance due to its extremely tall, massive and strongly laterally compressed body, with an almost circular profile in cross-section. The head is relatively small in relation to the body, and the eyes are also small compared to the fish's size. The mouth is small, sub-inferior (positioned below the snout) and extremely protractile (can be extended like a tube to suck food from sediments), without barbels. The scales are large, deciduous and abundantly covered with thick mucus that gives the fish a characteristic strong and unpleasant smell when handled. Coloration varies considerably with age and habitat: young specimens have silver scales with dark green or black backs, while adults develop shades of bronze, copper, rust or even brownish-red, especially in deep lakes. In rivers the coloration remains lighter (silvery-yellowish), in marshes it becomes rusty, and in deep lakes it acquires reddish-brown tones. The fins are relatively long, dark brown or bluish in color, an aspect that differentiates the bream from the similar species Blicca bjoerkna (silver bream). The caudal fin is deeply forked, with the lower lobe longer than the upper one. The lateral line is complete and curved. A distinctive feature is the belly ridge (keel), lacking scales on a portion. Average dimensions are 30-50 cm and 500g-1kg, but under optimal conditions it can reach 70-85 cm and 6-7 kg.
Habitat & Distribution
The common bream prefers exclusively slow or still waters with muddy or sandy bottoms, avoiding areas with strong currents or rocky bottoms. In the Danube Delta, optimal habitat includes permanent lakes with moderate depths (2-8 meters), marshes with vegetation at the edges, wide channels with very weak currents, and confluence areas of branches where fine sediment deposits abundantly. The bream is a strictly benthic fish, spending most of its time on the water bottom where it searches for food by systematically grazing the mud. In rivers, it occupies the deeper and clayey sections, in marshes it prefers areas adjacent to reed and bulrush thickets, and in lakes it seeks sandier bottoms. Small specimens form extremely numerous and compact schools, often numbering hundreds or even thousands of individuals, which move in regular and predictable "routes" - favorite paths where they can be found almost constantly. As they grow, breams become more solitary and gather in large groups only during the breeding season and towards winter when they migrate to deeper areas. In winter, activity drops dramatically and fish retreat to deep areas (the pits of the Danube or lakes) where they remain gathered in dense schools, feeding sporadically. The species tolerates a wide range of temperature conditions (from near 0°C to over 25°C) and can survive even in waters with lower oxygen content, although it prefers well-oxygenated waters.
Behavior and Feeding
The common bream is a strictly benthic omnivorous fish, with a diet based almost exclusively on organisms living on or in bottom sediments. The main food consists of midge larvae (chironomids), oligochaete worms living in mud, mollusks (snails and small bivalves), benthic crustaceans, plankton and aquatic plants. The feeding method is characteristic and extremely efficient: the bream uses its very flexible and protractile mouth to suck in sediment like a vacuum cleaner, subsequently filtering the food through powerful pharyngeal teeth and expelling the remains. In years with insufficient food, breams gather in huge schools and methodically "sweep" the water bottom, creating long ribbons of disturbed mud in their wake. Feeding activity is intense early in the morning and late in the evening, but can continue sporadically throughout the night. During the day, schools rest in deeper areas or under shelters of floating vegetation. Social behavior is extremely developed, coordination within schools allowing efficient exploitation of food resources concentrated on certain favorite routes ("bream roads"). Large specimens can become aggressive and opportunistic omnivores, occasionally consuming fry and eggs of other fish. In autumn, before winter, the bream intensifies its feeding for reserve accumulation, a time when it becomes extremely active and offers the best opportunities for anglers. During the breeding season, males develop white nuptial tubercles (breeding buttons) on the head and back.
Life Cycle & Reproduction
The common bream reaches sexual maturity relatively late, at the age of 3-7 years, depending on environmental conditions and food availability. Reproduction takes place in spring, between April and July, with a peak in May-June, when water temperature constantly reaches 17-18°C. At lower temperatures or sudden weather changes, egg deposition is temporarily interrupted, being resumed when conditions become favorable. The breeding period extends over approximately 2 weeks, fish gathering in large schools in shallow areas (0.5-2 meters) rich in submerged vegetation or at edges with clumps of reeds, bulrushes and other aquatic plants. The "spawning" is noisy and spectacular, males being very active and competitive. The female lays an impressive number of eggs - between 150,000-300,000 per female depending on size - which have a diameter of 1.6-2 mm and are sticky, adhering to aquatic plants, roots or even mineral substrates (pebbles, gravel) if vegetation is absent. Fertilization is external, males spraying the eggs with sperm immediately after deposition. Hatching occurs after 3-12 days depending on water temperature, larvae temporarily attaching to plants until yolk sac absorption. Fry begin to swim freely after a few days and initially feed on fine zooplankton. Growth is rapid in the first year, bream reaching 8-12 cm. The breeding potential of bream is enormous in shallow waters with abundant food, this tendency for excessive proliferation being naturally controlled by predatory fish (pike, zander, catfish) which intensively consume fry and juveniles.
Conservation Status
The common bream is classified as "Least Concern" (LC) by IUCN globally, being a common, widely distributed and stable species in most of its European range. In the Danube Delta and lower Danube basin, the species is abundant and does not face major threats, with populations being healthy and productive. The bream does not benefit from special protection measures in Romania and fishing is permitted without minimum size restrictions, with compliance with the general prohibition period for reproduction (April-June). However, at the local level, populations can be affected by eutrophication of waters (leading to oxygen depletion and changes in benthic composition), chemical pollution affecting the benthic fauna it depends on, hydrological modifications (river regulation, marsh drainage) that reduce breeding and feeding habitats, and overfishing in certain concentrated areas. In some regions of Europe, the bream has become a problematic species in degraded salmonid waters, where the absence of natural predators allows excessive proliferation and competition for resources with native species. Due to its remarkable adaptability and massive reproduction capacity, the bream is considered a good indicator of water eutrophication status - very high densities usually signal nutrient-rich waters but with low species diversity. Conservation of bream in the Danube Delta does not require special measures, but maintaining water quality and natural habitats is essential for population balance.
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