Río Izoria, Aiara, Álava, Spain

There are many reasons to study and investigate this biotope. Apart from the personal satisfaction of creating it, I also felt the desire to show the world this “unknown” and exciting cyprinid – Phoxinus bigerri.

Having it so close to my home (just 2km) encouraged me to give my contribution to enriching relatively little data on this fish and its biotope.

The 240L aquarium is set up with 2 external filters (Oase BioMaster 350) with a flute-type water outlet from the top to imitate the waterfall of the well. The Eheim Vivaline aquarium has dimensions 120x40x50cm.

I would like to point out that these 30 specimens of Phoxinus bigerri were caught unharmed with a fishing net. After keeping them in the aquarium, respecting and recreating their biotope as much as possible, they were released into their original habitat.

I kept these different fish imitating their seasons of the year with the intention of being true to nature, because each of the 4 aquarium photos has a different and real story.

Photo 1 – Summer.

The sun shines brightly and its rays are felt at the bottom of the river. Riverine vegetation near the river takes advantage of the heat and moisture captured through roots to ripen its fruit. Like this Viburnum lantana, whose green berries turn a spectacular cherry red color in early summer. The water level has dropped due to the lack of precipitation, but the waterfall in the well continues to supply the pool with a thin layer of water, which flows gently along the rocks. I tried to imitate it by lowering the flow rate of the water coming out of the filters.

The water parameters were very easy to bring back to the aquarium, given that the water in my house has exactly the same values as the recreated biotope, given the proximity to the river of no more than 2km.

• Water parameters: PH 8.1, KH 8.0, GH 196 (dH 11.0).
• Average water temperature in the aquarium is kept at 22ºC, with the use of the fan.

Photo 2 – Autumn.

Hurricane wind gusts in November forcefully penetrates through the water column, a dry branch of a nearby tree can be seen stuck. The remaining leaves of the trees surrounding the pool stain the water with tannins and serve as shelter for the Phoxinus from the storm.

Tannins – are substances that contribute to the benefit of the aquatic environment. They have properties that help prevent bacterial and fungal infections, protect against mucogenesis and also have antioxidant capacity. They also stimulate the reproduction of fish, as colonies of infusoria settle in the foliage – food for the newly born fry.

The rocks are calcareous and covered in algae. To imitate the silty bottom, the substrate is a fine, dark-colored sand.

Phoxinus are very curious and grateful beings, they come closer while they are being fed. But they are also jumpers by nature and in the open aquarium, they jump up to 8cm out of the water trying to catch food. A show worth seeing. However, it is necessary to place a lid over the aquarium, to avoid possible casualties.

• Water parameters: pH 8.05, KH 8.0, GH 196 (dH 11.0)
  Average aquarium temperature of 18ºC.

Photo 3 – Winter.

Storms, strong thunderstorms and hurricane winds manage to uproot a tree which, dragged by the current, remains semi-submerged in the pool, stuck between stones on the bottom. The current of the waterfall is strong combined with a heavy rain, and continues to agitate the silty bottom, the branches and the leaves, facilitated by the shallow depth of the well.

Winter storms disturb Phoxinus, very curious fish that scrutinize every nook and cranny between leaves and trunks. Due to their restless nature it is difficult to photograph them.

• Water parameters: PH 8.1, KH 8.0, GH 231 (dH 13.0).
• Aquarium water temperature of 15º.

Photo 4 – Spring.

The sun does not yet shine with full strength in this biotope. The river’s riparian vegetation grows luxuriantly in the environment, where rainy and sunny days alternate, taking advantage of the soil’s humidity.

Towards the end of the season we begin to see the fruit of trees and shrubs, such as Viburnum lantana, a shrub that partially submerges its branches in the water of this pool. Although Viburnum lantana is classified as a shrub, the plant can reach 4 meters in height. It has spectacular branches and fruits, which in this season are whitish green in color, it grows in calcareous soils and its branches and fruits have anti-inflammatory and astringent properties.

During this season, storms and rising water levels are frequent, and these branches are always directed downstream, following the course of the current.

The Kiskailu, as Phoxinus bigerri is known in the Basque Country, feels safest among the vegetation, where it frolics and occasionally jumps out of the water.

The flowing water reaches the pool through the waterfall, in spring it does so with an intermediate force, favoring oxygenation and gas exchange. In the aquarium this function performs the filter with the flute outlet, which tries to imitate the waterfall.

• Water parameters: pH 8.0, KH 8.0, GH 214 (dH12.0)
• Average water temperature in the aquarium 20ºC.