bam Demanding level

Río San José, Horquetas, Sarapiquí, Costa Rica

Sponsored by

Costa Rica, Heredia, Horquetas / Sarapiquí / Heredia

This 200L aquarium represents the high water flow in the San Jose River, where fish move across algae-covered rocks in crystal clear water. The fish are divided between those that inhabit the open waters and those that find their territory between the crevices of the stones.

Submitted by
Andrés Cordero Porras
Approved by
Juan M. Artigas Azas, Jairo Arroyave & Michael Köck
10.3182783, -83.8910141
Geographical region
Central America
Drainage Basin
Río San Juan
River catchment
Braulio Carrillo National Park in Heredia
Water body type
Water body name
San José
Water body part
Water body course
Middle course
Water body: tributary of
Tributary name
Río Sarapiquí

Videos above and below water

Water Chemistry

Water information

Water type
Fresh water
Water color
Clear water
Water transparency
Concentration of sediments
Water temperature
25 °C
Water flow/curent

Chemical parameters

Dissolved Oxygen
89 %

Aquarium information

Aquarium description

Set-up date
January, 2023
Aquarium decoration

The stones that were used are similar in color and shape to those of the San Jose River. The stones vary in size to shape the flow of the river, between these stones gravel of different sizes and colors was used to replicate the natural environment.

A 10-hour photoperiod with 6500k LED light was used to achieve the green algae on the stones.
This spectrum of light replicates the one seen in the river.

Aquarium equipment

Filtration is handled by a PenPlax Cascade 1500 canister filter. It holds 5 baskets with media: 1 for mechanical media and the other 4 are used for biological media.

Fish care

The aquarium recreates the open waters of the rapids on the San José River. The middle part of the water column is inhabited by the Astyanax aeneus fish and the crevices in the stones and bottom of the aquarium are the habitat of Amatitlania siquia.

Astyanax aeneus are very voracious fish, feeding on particles in the water column, on the surface, and even on any food found in the substrate. They feed in groups, while the Amatitlania siquia are more fearful fish and only move from their territory when they feel safe. These two grabbed a corner of the aquarium for each other and defend their territory.

Plant care


Water care

The aquarium water has a high evaporation due to its temperature, so the percentage evaporated is replaced manually every two days and the water is changed every 8 days with 25% water changed. The filter is cleaned and maintained every 2 months to maintain the high water flow required by Astyanax aeneus.


100 cm
50 cm
40 cm
198 L

Substrate in aquarium

Stone form
Submerged terrestrial vegetation

Comment by the expert

Michael Köck: The aquarium matches almost 100% the natural conditions. I like the fact that Astyanax dominate the aquarium like they do in most of the mesoamerican rivers of the atlantic side, and the algae covered rocks that give the tank the expression of gravity and age. I only would have liked to see effect light painting sun beams into the tank. Overall: very well done.

Juan M. Artigas Azas: Lovely aquarium! I can imagine how easy it is to get hypnotised by its beauty and calmness tank!

Jairo Arroyave: BAM is a good representation of the BIN, but technically it is not a very challenging BIN/BAM. Lacks several fish species, but the ones included are presented in harmony with the rest of the components of the model. Overall, and despite the relative simplicity of this biotope, the model is indeed a good representation of the habitat in nature.