The shady bank of Ipoly River, Hungary. Underwashed riverside

_st place in Biotope Aquarium Design Contest 2022

Volume of aquarium: 247.5 liters

Dimensions of aquarium: 110X50X45 cm

List of fishes: Blicca bjoerkna, Rutilus rutilus, Alburnus alburnus, Proterorhinus semilunaris, Unio tpictorum, Viviparus acerosus, Corbicula fluminea, Theodoxus fluviatilis, Sphaerium corneum, Pisidium amnicum, Orconectes limosus.

List of plants: Ceratophyllum demersum, Myriophyllum spicatum.

Description of Decorations and Substrate: The major concept was to portray a river section, where a cut-off side followed by a riffle section of a mountainous river Ipoly. Where this two parts meet, the relatively strong current of river may form various features, such as pools and reserves including big stones at riverbed. The large-grain sand were selected and cleared by the current which makes the habitat more heterogeneous and ideal home for current preferring fishes and invertebrates especially for the larvae of mayflies and dragonflies. Medium and large-sized andesite stones were used since this type of rock is the main type of Börzsöny Mountain, and occurs in the riverbed also. The grey river sand is from a DIY hardware store, it is has the same colour and grain size as in the Ipoly. Driftwood was collected from the riverbed. I especially searched for the ones without bark, which were laying under the water for a longer time and darkened due to the log-term exposition to freshwater. The fragment of branches are mostly from poplar (Populus sp.), alder (Alnus glutinosa) and white willow (Salix alba). Smaller secondary roots of various Salix species were also used to make the riverbed more diverse. Leaf litter was collected at the riverbank including species such as alder (Alnus glutinosa), white willow (Salix alba), field maple (Acer campestre), poplar (Populus sp.), and white elm (Ulmus laevis).

Description of Equipment: Homemade top cover and light with two Juwel Colour-Lite T8 Tubes + IKEA spotlights. Atman CF 1000 external filter.

Water Parameters: Regular freshwater with slight content of hydrocarbons, no heating, temperature is around 22°C. 10 % water change in every 10 days with tap water stored in buckets for several days before use.

Additional Info: I have created the aquarium in last October. I was about to see, study and enjoy a little part of my favourite small river at home. Juvenile, mostly half-year-old fishes and decoration elements were collected directly from the river. After the first setup, I realized soon that many species have overgrown very fast the dimension of the 247-liter fish tank, thus I had to reduce the fish population to 17 fish, mostly small individuals around 4-5 cm. As the external filter operates smoothly, the water became clear and most of the algae, weed and smaller organisms disappeared from the biotope or fishes ate them by the end of the month. The water and the decoration are a little bit unduly clear, thus I recently added some freshly collected logs and dead fallen leaves from the freezing cold river to make it a more genuine piece of art, especially for this competition.

Aquarium video:

Description of the Area Surrounding the Biotope: The Ipoly river arrives from Slovakia to the North of Hungary, and with its 143 km Hungarian length it is the only river enters on the left side of river Danube. This is a relatively fast and shallow river is one of the most pristine rivers of the country, even though it meander close to many smaller villages before reaches the main river. This waterbase is the home of dozens of current preferring fishes, such as barbel (Barbus barbus), chub (Leuciscus cephalus), asp (Leuciscus aspius) and also hosts many small and protected species. Ipoly has a flash-flood risk as compare to other the Hungarian rivers, it can easily change quite rapidly within a day especially in rainy seasons. The shallow and gravel-covered areas usually with only 10-30 centimeters of water, but at the outer part of the meandering Ipoly can hold some quite deep, 2-2.5 meters deep pools, with significant quantity of driftwood on the bottom. When the flood comes, the river turns muddy, because of the smaller streams which transport substrate from the nearby hills. At low water level the water of the river is quite transparent, with tipical goldish colour, because of the surrounding floodplain forest, from where leaves and branches arrive into the river, paint its water darker. The amount of sediment transported by the river shows a seasonal variation; the most of the sediment transported in spring and the first half of the summer period, after august the river became more transparent due to lack of sediment and decreasing activity of phytoplankton in early autumn.

Description of the Underwater Landscape of the Biotope: Due to the transparent and shallow water, smaller fishes usually prefer spots at the river margins. Especially at the edges of the turns there are riffles, trenches or cut-offs with roots of big trees. This shady area helps the younger fish to hide from their predators, and here they live in great numbers. Many smaller species like the European bitterling (Rhodeus amarus) or the Danube whitefin gudgeon (Romanogobio vladykovi) prefer these zones, but also the young barbel, chub, vimba bream (Vimba vimba) or the common nase (Chondrostoma nasus) hides here to avoid their predators like the fast and huge asps and large chubs and idefish (Leuciscus idus). The biotope shows this shady zone, where bigger stones made the driftwood stay there, and small fish can find shelter around them.

Description of the Habitat Parameters: Water is semi-transparent, goldish, but when it is flooded it became muddy of course. The warmest summer days can heat up the water temperature up to 22-23 Celsius degrees.

List of Fishes and Invertebrates Occurring in the Nature Biotope: Leuciscus aspius, Leuciscus cephalus, Alburnus alburnus, Rutilus rutilus, Alburnoides bipunctatus, Blicca bjoerkna, Vimba vimba, Chondrostoma nasus, Barbus barbus, Romanogobio vladykovi, Rhodeus amarus, Cobitis elongatoides.

non-native species: Pseudorasbora parva, Neogobius melanostomus, Ponticola kessleri & Orconectes limosus.

List of Plants Found in the Nature Biotope: Salix alba, Alnus glutinosa, Ceratophyllum demersum, Myriophyllum spicatum.

Threats to the Ecology of the Biotope: Polluting the natural waters of the country is a huge problem in Hungary. Although in the last decades many things changed, people still think rivers are ideal to throw their waste in to them. The water conditions are usually less optimal for sensible species around the towns and villages, but because of the fast current, local pollutions – which occur especially after heavy rains – can leave these areas quite quick. The biggest problems for the biotope are the invasive animal and plant species. The asian calm (Corbicula fluminea), the spiny-cheek crayfish (Orconectes limosus) cause big problems, such as non-native fish species like different goby-species (Ponticola kessleri & Neogobius melanostomus) or the prussian carp (Carassius gibelio). They have the same impact as any other aggressive alien species: takeover the habitat from native species, they can spread different diseases and also they are food-competitors for them. And there are also plant species, who can also change the shoreline of the river dramatically. Tree species like box elder (Acer negundo) or false indigo-bush (Amorpha fruticose) grow much faster than local tree species which can disappear from an affected area.

Sources of Information:
Weiperth A., Bányai Zs., Ferincz Á., Juhász, Sevcsik A., Staszny Á., Szalóky Z., Tóth B. 2020: Overview of crayfish and fish fauna researches in the Hungarian section of the River Ipoly/Ipel. – Pisces Hungarici, 14, 33–44.

Csipkés R. & Szatmári L. 2011: Data to the fish fauna of the Hungarian upper section of river Ipoly and its tributary streams. ¬– Pisces Hungarici, 5, 73–82.

Duna-Ipoly National Park webpage: