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Old Danube, Gemenc Forest, Hungary

Sponsored by

Hungary, Dél-Dunántúl, Tolna

As a Hungarian, our native waters are close to my heart, so I decided that my next aquarium will be made from my homeland. Since I have always been interested in the world of oxbows, I chose the Old Danube in Gemenc Forest which has an extremely rich flora and fauna.

I chose a part near the coast, where the water is slow-flowing, the bed is covered with silt, branches, and terrestrial plant parts. This habitat provides an ideal hiding place for the one of our smallest fish, the Sunbleak (Leucaspius delineatus). Due to the capabilities of the aquarium I was able to create an ideal habitat for them with plenty of hiding places and enough swimming space.

Submitted by
Klementina Keresztes-André
Approved by
Gireg Allain & Aleksey Malyshev
46.2030029, 18.8787174
Geographical region
Eastern Europe
Drainage Basin
River catchment
Water body type
Oxbow lake
Water body name
Old Danube
Water body part
Flood plain
Water body course
Water body: tributary of
Tributary name

Videos above and below water

Water Chemistry

Water information

Water type
Fresh water
Water color
Clear water
Water transparency
Concentration of sediments
Water temperature
21 °C
Water flow/curent

Chemical parameters

11 mg/l
5 mg/l
Dissolved Oxygen
70 %

Aquarium information

Aquarium description

Set-up date
April, 2022
Aquarium decoration

The substrate was made from a mixture of sand and gravel, to which I added larger river stones as the same color which found in the nature. I made the sediment covering the soil from tree and reed leaves.

I tried to model the shallower part of the Old Danube coast, where the riparian vegetation provides a suitable hiding place for sunbleaks. For this reason I used driftwoods, branches, withered reeds and wild grape stolons as decorations. I supplemented this with live plants: water mint (Mentha aquatica), silverweed (Potentilla anserina) and Salvinia natans.

Aquarium equipment

Filtration: DIY canister filter – 25 Watt, 1200 l/h
Lighting: DIY led reflectors – 2×20 Watt, 6500K

Fish care

The water level is quite low, as in nature so marsh plants can develop properly. The water mint roots provide a great hiding place for sunbleaks that in nature take shelter in dense vegetation from predators. Although they are not threatened in the aquarium, I have observed that they still feel safe near the roots.

The water is around 21°C, and the flow is neither too strong nor too weak: thanks to this, they swim around in a loose group. To keep them healthy and energetic I feed them only live food like bloodworms, tubifex, brine shrimp and Enchytraeus buchholzi.


  • Leucaspius delineatus (Cyprinidae) – 30


  • Lymnaea stagnalis (Lymnaeidae)
Plant care

Since the plants I have planted grow quite quickly, they require regular cutting especially the water mint. I do not feed the plants, as there are many decomposing substances in the water such as tree leaves and reeds so the plants use decomposition products and help to keep the water clean like in nature.

Aquatic plants:

  • Salvinia natans (Salviniaceae)

Wetland plant

  • Mentha aquatica (Lamiaceae)
  • Potentilla anserina (Rosaceae)
Water care

I change one third of the water every two or three weeks taking care of the sediment on the substrate not to mix it up, otherwise the filter will absorb it. Aquarium water is cooled by air conditioner which is very important for these cold water fish especially in the summer heat.


90 cm
35 cm
27 cm
85 L

Substrate in aquarium

Stone form
Submerged terrestrial vegetation



Comment by the expert

Gireg Allain: This aquarium is a wonder of realism! The reconstitution of the biotope is not only very precise, but also particularly aesthetic. The arrangement of faded reeds is superb, and reminds a little of the forest environment of the biotope. The soil covered with decaying plants is particularly natural and constitutes a perfect atmosphere for the Lymnaea. The Leucaspius delineatus seems perfectly at ease (but perhaps they are a little too many?). The aquarium data is clear and accurate, the maintenance is solid, and this installation is made to last. It’s beautiful!

Aleksey Malyshev: The aquarium is decorated in the same way as in a natural pond, but 85 liters is not enough for 30 fish. They would be better off in 150-200 liters.