Rio Guarumo – Panama; rocky shallow water in the dry season

_st place in Biotope Aquarium Design Contest 2022

Volume of your aquarium: 98 liters

Dimensions of your aquarium: 80 x 35 x 35 cm

List of fishes: Cichlidae:
Cryptoheros nanoluteus (3)

Poecilia mexicana (4)

List of plants: None

Description of Decorations and Substrate: Substrate is a mix of classic sand, and some larger gravel types, to recreate the look of the river button I’ve seen in both videos and pictures from Rio Guarumo. Then I’ve chosen pumice stones in different sizes to make the rocky area look more like the are from the video. Pumice stones are beautifully shaped and looks a lot like Central American river stones. Especially with a brownish algae cover.

Then I have chosen to add a couple of Crater Wood pieces to illustrate fallen trees and logs ending up on the river button. All though that is not visible in the video material, it is pretty common in those river types – especially during dry season.
Finally I’ve added som branches and leafs.

Description of Equipment: Aquarium: OW 98 litres Opti White

Filtration: Fluval 207 cannister filter – 780 L/h.

Lightning: two IKEA Nymåne lamps with some special Osram Parathom GU10, 550 lumens 4000 k, LED spots. The spots are trying to imitate the single sun rays penetrating through the water of the forrest stream.

Two Sonoff S26 smart plugs

Water Parameters: Temperature is 26 celsius. Ph is about 7,6. KH is 5. GH is 8.

Additional Info: 25% waterchange every week.

Aquarium video:

Description of the Area Surrounding the Biotope: The Rio Guarumo is located in the northern part of Panama, in the province of Bocas del Toro, close to the border of Costa Rica. The river flows into Laguna de Chirique, which is connected to the Atlantic occean. The latitude of Rio Guarumo is 8.9979, and the longitude is -82.18111 with the GPS coordinates of 08° 59′ 52.43″ N and 82° 10′ 51.99″ W.

There is some agriculture in the area, and both bananas, cocoa and coffee plantations are common here.
There are periods of low rainfall in March and September–October, and periods of high rainfall in July and December. During the rainy season the river is broad and fast flowing, but it gets narrow and slow moving in the dry period.
Forest is covering much of the riverbank along Rio Guarumo, and with both jungle and rain forest in the nearby area it is a relatively lush area. Which is confirmed by the fact, that there is recorded over 300 species of plants in Bocas del Toro alone.
In areas with poor light the lowest layer is dominated by epiphytes and ferns. In disturbed and recovering forest, the following trees are common: Cotonron, Cerillo, Wild Plum, and the Fig Higueron.
Over 32 mammal species have been recorded in the area. The Paca, white-throated Capuchin, night monkey, sloth and striking anteater are also common in the forest areas.

Description of the Underwater Landscape of the Biotope: The landscape is dominated by rocks in almost any size. Some places in the river the bottom is only rocks, other places there is sandy areas too.
The life of the river varies quite a lot from rainy to dry season. This also affects underwater life. During the rainy season the current is much stronger and the river wider. In this season the rocky bottom serves as hiding place for many fish species. In the dry season, when the water gets slowly, the sediment falls to the bottom. Leaf’s, logs, and branches do the same. The river is lacking in vegetation and mostly consists of rocks, logs, and leaf litter.
The water is clear, but can have low visibility when the current gets too strong.

Description of the Habitat Parameters: Water temperature in the dry season: 27°C. pH 7.5. dH 3. kH 3. 70 mS.

List of Fishes and Invertebrates Occurring in the Nature Biotope: Cichlidae:
– Amatitlania nigrofasciata
– Cryptoheros nanoluteus
– Chuco microphthalmus
– Cribroheros alfari

– Poecilia butleri
– Brachyrhaphis sp.
– Poecilia mexicana
– Alfaro cultrata
– Poecilia gillii
– Phallichthys amate pittieri

List of Plants Found in the Nature Biotope: None

Threats to the Ecology of the Biotope: As much of the rest of the area Rio Guarumo is also threatened by human activities, such as agricultural expansion and pollution. The aquatic life is, however, especially threatened in Rio Guarumo these years; over the last 6-7 years the government has been doing excavation work to build up river walls to prevent the river from flooding the nearby habitation.
It is estimated that the walls can prevent 10.000 people from getting flooded. And although it is appropriate for humans, it is surely a great thread for many fish and other lifeforms in and around the river.

Sources of Information:
1) Video showing C. nanoluteus in Rio Guarumo –
2) Article describing the excavation work in Rio Guarumo:
3) Article describing fish and water parameters in Rio Guarumo, by Alf Stalsberg:
4) Website describing the fauna of the area:
5) Book describing both C. nanoluteus and Rio Guarumo: “Små cichlider” by Benny B. Larsen and F. Ingemann Hansen – ISBN: 978-87-7857-534-0
6) Interview with Frank Ingemann Hansen (author of the book above and expert in fish and cichlids) about P. mexicana and Rio Guarumo.