bam Easy level

#7722 Río Izoria, Valle de Aiala, Álava, Spain

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Spain, Álava, Ayala

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 2 km) encouraged me to give my contribution to enriching relatively little data on this fish and its biotope.

The 240 liter 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.
Submitted by
Asier Murga Arteta
43.0541344, -3.0439744
Geographical region
Southern Europe
Drainage Basin
Valle de Aiala
River catchment
Water body type
Water body name
Río Izoria
Water body part
Water body course
Middle course
Water body: tributary of
Tributary name
Río Nervión

Videos above and below water

Water Chemistry

Water information

Water type
Fresh water
Water color
Clear water
Water transparency
Concentration of sediments
Water temperature
18 °C
Water flow/curent

Chemical parameters

178 mg/l
8.0 mg/l
Dissolved Oxygen

Aquarium information

Aquarium description

Set-up date
May, 2023
Aquarium decoration

The stones come from the river. I put some fine, grayish sand between the joints of the stones to simulate pool silt.

Each season of the year corresponds to different decorative elements – submerged terrestrial vegetation, branches, leaves. I believe that to be faithful to nature it is necessary to imitate it as it is, and we must pay close attention to climatological conditions and their changes.

For example, I observed that in the spring the semi-submerged branch of Viburnum lantana had green fruits, and in the summer the fruits turned very red. Or, in autumn there are many more leaves than in spring.

In winter the current and strength of the waterfall are much greater than in summer – that’s why I put a flute inflow to imitate that waterfall, and gave more or less flow depending on the season of the year to imitate.

In autumn and winter there is a lot of wind, so the branches break and fall into the pool, which does not happen in summer, there are many differences between the 4 seasons of the year.

I also put a net over the aquarium protected from jumping Phoxinus, as they are used to jumping out of the water to catch insects.

Aquarium equipment

The filtration consists of 2 Oase BioMasters of 1100L/h and sponges as pre-filter. The filter material mainly consists of Seachem Matrix and plastic bioballs as the first filtration stage.

The filters are placed on each side of the aquarium, with an outlet from one side to the other along the aquarium to imitate the small waterfall of the Río Izoria.

The heaters installed inside the filters are turned off and in the summer a JBL fan was used to lower the water temperature by 3ºC.

The lighting is by 2 Eheim LED Daylights with a function that automatically imitates sunrise and sunset to make everything more natural.

Fish care

For the well-being of the fish, the first thing I did was to trace the water parameters of their habitat as well as to use almost entirely the elements of that biotope for the set-up. I also simulated the seasons of the year and covered the tank with a net to prevent the Phoxinus from jumping out.

It was important to maintain an adequate temperature for them, in the hot months with the help of a fan.

I provided them with shade and shelter (such as rocks and leaves).

I did a generous weekly water change of 30-40%, which is the best care, and also renew every month the denitrifying bacteria with Bio Digest and Bio Trace.

Feeding is very important, I fed them Tropical Pro Defense dry food several times a day in small portions. This food has probiotics, strengthens the fish and helps the digestion. Once a week I fed them live artemia to keep awaken their wild instinct for hunting live food, just like in nature.

All this care made it possible to stimulate their reproductive instinct. Also I was lucky to catch them in May, when the courtship begins.

The males displayed all their potential, going from a gray color to a powerful red color in the fins, chin and lower body, with green flashes on the sides. And the most surprising and fascinating thing, something that I didn’t know until I saw it with my own eyes, was to see how males developed white nuptial tubercles on the head. A kind of royal crown to impress the females – spectacle worth seeing.

This magical moment lasted only 2 weeks, then the males turned the same gray color with black spots as the females.

Plant care

In the small waterfall of the Izoria river there is no vegetation, apart from the algae that grow on the rocks.

Water care

As mentioned above, I do water change water every week of 30-40%. I renew the denitrifying bacteria every month.

When I notice that the flow rate of the external filter drops, I clean the filter with aquarium water. Every time I clean filter, I add the Bio Digest bacteria. I clean the filter approximately every 4 months, but I change the sponges every month, this change does not have any impact on the water, since I only put new sponges and it is done very fast, so the biological filtration remains intact.

I have never had a rise in nitrites and nitrates remain practically at 0.

The water outflow is flute type to mimic the small waterfall of the river. Thus the water is perfectly oxygenated and favors the exchange of gases.


120 cm
40 cm
50 cm
240 L

Substrate in aquarium

Stone form
Submerged terrestrial vegetation