By Natasha Khardina
Presenting the top winners of the 5th edition of the Biotope Aquarium Contest (BAC2024), organized by the BIOTOPE AQUARIUM Project (BAP), an independent educational project that aims at motivating aquarists to study the surrounding aquatic environments by applying their knowledge in the recreation of biotope aquariums.
The Biotope Aquarium Contest 2025 (BAC2025) has once again carried forward a quiet revolution in the aquarium world: transforming precise field research of natural habitats into public education. Instead of rewarding artistic layouts alone, BAC demands scientific documentation – photographs of the original location, species lists, substrate analysis and systematic notes – and celebrates those who faithfully translate wild habitats into living aquariums. This year’s edition, supported by global industry partners, reaffirmed the contest’s dual mission: to inspire aquarists and to raise awareness about fragile aquatic ecosystems.
In fact, BAC2025 reached a milestone with a record number of entries, reflecting the contest’s growing influence and the rising interest in authentic biotope recreation worldwide. Participants from across continents – from the flooded forests of the Amazon to the rocky streams of Indonesia — submitted detailed documentation, making this year not only the largest but also one of the most diverse editions in the history of the contest. This surge in participation underlines the global resonance of BAC’s message: that aquariums can serve as living classrooms and ambassadors for conservation.
This year also marked the integration of VietBAC — Vietnam’s national biotope competition — into BAC2025. This step represents a milestone toward the unification of standards, judging parameters, and educational goals, ensuring that local initiatives contribute to a coherent global framework.
The name of Heiko Bleher has long been synonymous with the exploration of biotopes. Over decades of expeditions, publications and photography, he created a body of work that taught aquarists to look at their tanks not as ornaments but as miniature ecosystems reflecting real rivers, lakes and floodplains. His work often combined the thrill of adventure with careful documentation – a model that BAC enacts through its rules today. Yet Bleher was not simply an icon: his later years were marked by personal complexity and controversy, a reminder that every legacy is both scientific and human. As many recall, “Heiko taught us to read habitats – and to feel responsible for them.”
The passing of Heiko Bleher in August 2025 was a turning point for the global aquarium community. For many, it felt as if the last great explorer of ornamental ichthyology had left the stage. Yet his influence continues tangibly through the Biotope Aquarium Project (BAP), an initiative he helped shape by contributing archives, photographs and field data. Today, BAP and BAC work hand in hand: one as a repository of scientific and visual documentation, the other as a platform engaging aquarists, educators and sponsors in carrying the legacy forward. In this sense, BAC2025 was not just a contest but also an act of remembrance, where every BIN-submitted photo and every recreated stream bed extended the thread of Heiko’s work into the future.
This year’s contest placed strong emphasis on reproducibility. Participants submitted BIN (Biotope In Nature) evidence and were evaluated by an international jury of scientists, editors and explorers. Sponsors contributed prizes and publicity, but the true value remained educational: a growing, shared repository of biotope reconstructions that can inform future research, museum displays and teaching programs. In effect, BAC has become a distributed method of preserving field knowledge that once resided only in the notebooks of solitary explorers.
Beyond trophies and social media posts, the contest generates materials that teachers and museums can use. When a winning entry documents an endangered waterway or a rare species composition, that story can be amplified in classrooms, museum exhibits and outreach programs supported by sponsors. Companies that back BAC are not just providing prizes; they are helping to transform niche hobbyist interest into broader public awareness of conservation. As one participant observed, “The contest builds a reproducible corpus of biotope knowledge — exactly the kind of legacy Heiko would have wanted.”
For those who knew Heiko personally, the contest is also a reminder of unfinished work: preserving archives, protecting intellectual heritage and ensuring that field data remain accessible. Institutional partners – museums, sponsors and initiatives like BAC – now bear the responsibility of translating one explorer’s lifetime into durable educational assets. Supporting BAC2025 is therefore more than simply sponsoring a competition; it is an active way of safeguarding the memory and mission of one of the most restless and inspiring figures in the aquarium world.
For those who knew Heiko personally, the contest is also a reminder of unfinished work: preserving archives, protecting intellectual heritage and ensuring that field data remain accessible. Institutional partners – museums, sponsors and initiatives like BAC – now bear the responsibility of translating one explorer’s lifetime into durable educational assets. Supporting BAC2025 is therefore more than simply sponsoring a competition; it is an active way of safeguarding the memory and mission of one of the most restless and inspiring figures in the aquarium world.
North America – sponsored by FLUVAL
Approved by: Fritz Rohde (NANFA), John T. Baxter (Conservation Fisheries) and Lawrence Kent (NANFA).
BAM: Headwaters wetland, Pigeon River, Ontario, Canada, by Rui Sun (Canada):
“This 84L biotope aquarium recreates the shallow littoral wetland zone of the Pigeon River headwaters in Kawartha Lakes, Ontario. Inspired by field observations made during spring, the setup mimics the slow spring-fed water movement observed in nature, aiming to reflect the subdued, biodiverse, and functionally complex nature of this coldwater wetland habitat.
The aquarium features a sediment layer with naturalistic coloration, replicating the silt-mud and sand mix of the site. Submerged Ludwigia palustris provides vegetation structure, while scattered fallen reed stems and spawning sedges. The fish includes brassy minnows (Hybognathus hankinsoni), northern redbelly dace (Chrosomus eos), central mudminnows (Umbra limi), and marsh pondsnails (Ladislavella elodes), all of which are native to or observed in the original biotope.”
Central America & Caribbean – sponsored by AQUAEL
Approved by: Jairo Arroyave (UNAM), Juan M. Artigas Azas (Cichlidae.com) and Michael Köck (Goodeid Project)
BAM: Shallow Backwater Pool, Río San José, Horquetas, Costa Rica, by Andrés Cordero Porras (Costa Rica):
“This biotope highlights the role of Zygia longifolia roots in shaping habitat complexity. In a 420L aquarium, dim lighting mimics sunlight filtered through the forest canopy, casting soft beams on sandy substrate. Hollow root structures dominate the layout, providing shaded refuges for shy fish.
Surface and midwater species like Poecilia gillii swim freely, feeding on algae growing along exposed roots, while more timid species remain hidden. This natural behavior is evident in Cribroheros rostratus, which, both in the wild and in the aquarium, cautiously emerge from the shadows under the roots. Initially unseen, they gradually appear and exhibit earth-eating behavior, rhythmically sifting sand in search of food. This setup replicates not only the physical structure of the Río San José backwater but also its behavioral dynamics, offering a living, interactive ecosystem that rewards patient observation with an authentic glimpse into freshwater fish ecology.”
South America – sponsored by Ocean Nutrition
Approved by: Roberto E. Reis (PUCRS), Antonio Machado-Allison (College of the Environment, Wesleyan University) and Pablo C. Lehmann (PUCRS)
BAM: Caño El Pozo, Orinoco basin, Venezuela, by Walter Vazquez (Argentina):
“My 200L biotope aquarium represents the banks coastal waters of Caño El Pozo, a stream belonging to the Orinoco River basin in the Colombian-Venezuelan Amazon. I based my own representation on images and first hand information from Ivan Mikolji and some of his articles. I used white silica sand for the substrate, the same as the original system.
The bottom contains remains of the fruit of Maurita flexuosa and its seeds, leaf litter, and I used branches, trunks, and roots to simulate the coastal zone. I also simulated the entry of Moriche palm leaves into the water from the surface with similar palm leaves for a more natural look.
I also used plants of the same genus found in the area, such as Cabomba caroliniana (replacing Cabomba furcata, since it is not sold in my country), Bacopa sp., Eleocharis minima, and Naja guadalupensis. The fish species used in the aquarium are Pristella maxilaris, Nannostomus eques and Paracheirodon axelrodi.”
Europe – sponsored by BIOTOPE AQUARIUM Project
Approved by: Alexey Malyshev and Francesco Denitto
BAM – single entry: Rocky canals, Palude del Capitano, Puglia, Italy, by Alessandro Crudo (Italy):
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 aquarium is a replica of a section of the aquatic site. A portion of the vertical limestone wall as found in several areas of the pool is highlighted. These vertical cuts in the rock are particularly evident near the submerged channels connecting the pool to the sea.
The seabed consists of fine white sand as present in the natural site. Limestone rocks, driftwoods and roots of semi-aquatic plants are also part of the site’s submerged landscape. On these substrates are sessile invertebrates such as the hydrozoan Cordilophora caspia and numerous vagile invertebrates such as Gammarus aequicauda, small gastropod molluscs such as Theodoxus fluviatilis and decapod crustaceans of the genus Palaemonetes.
A population of Aphanius almiriensis lives among the fractures in the rocks and aquatic roots. This fish species is currently only reported in Italy at this site. Other euryhaline fish species such as Atherina boyeri and Liza ramada, on the other hand, occupy the open water of the lagoon and are more widely distributed across Mediterranean brackish and coastal environments. These species tend to tolerate a broader range of salinity and temperature fluctuations, giving them a competitive advantage in less stable habitats.
In contrast, Aphanius almiriensis exhibits a more specialized habitat preference, often associated with microhabitats that provide shelter from predators and stable environmental conditions. This ecological specialization may contribute to its limited distribution and heightened vulnerability to habitat alterations.
Conservation efforts for Aphanius almiriensis should therefore prioritize the protection of its specific habitat features, including submerged vegetation, rocky crevices, and the overall water quality of the lagoon system.”
Africa – sponsored by BIOTOPE AQUARIUM Project
Approved by: Ad Konings (CichlidPress) and Anton Lamboj (UniWien)
BAM: Moliwe River, Southwest Region, Cameroon, by Frank Reinders (Germany):
“This 312L aquarium replicates the shoreline of the Moliwe River in Cameroon. Roots from riverside vegetation extend into the water, creating shelter and current breaks where Epiplatys infrafasciatus “rathkei” hunt for insects at the surface. Beneath lava rocks, Pelvicachromis kribensis “Moliwe” forage for biofilm and raise their fry in crevices. The substrate is free of sediment, and a strong current — produced by two circulation pumps and an external filter – prevents plant growth. The water temperature is kept at 26 °C to match natural conditions. The layout, built on a 130×60×40 cm footprint, uses lava rock structures colonized by algae. This setup was chosen to authentically recreate the dynamic, clean, and species-rich habitat of the Moliwe River, focusing on biological realism and natural behavior.”
Eastern Asia – sponsored by San Francisco Bay Brand
Approved by: Sun Kai and Zhou Hang
BAM: Unnamed Stream, Shiwandashan Mtns., Guangxi, China, by Yunfei Long (China):
“This 62L aquarium recreates a stream-slice from the southern foothills of Guangxi’s Shiwandashan Mountains, capturing the post-rainfall conditions of a near-bank slow-flow zone during early November’s dry season transition.
Exposed boulders –now colonized by Acorus gramineus and ferns – stand above receding waters, while leaf drifts and submerged branches create a refuge for Aphyocypris sp. and Araiocypris batodes. Submerged vegetation is nearly absent in this stream section. The rocks, minimally transported by water flow, are piled haphazardly while retaining crisp veining and angular edges – creating interstices where Aphyocypris normalis darts through. These stones are coated with diatoms, sustaining grazing by Liniparhomaloptera disparis, shrimps and snails.
This interesting biotope, now lost to environmental degradation, was documented by my friend during exploration. It stands as an ecological memorial to that lost ecosystem.”
Southern, Central & Western Asia – sponsored by JBL
Approved by: Friedrich Bitter (Amazonas Magazine) and Hans-Georg Evers
BAM: Lake of the Societies, Kolkata, India, by Debanjan Banerjee (India):
“The 135L aquarium is a small replica of the beautiful natural Lake of the Societies, Kolkata, India.
I was mostly motivated by seeing the fact that not much of data on the internet is available on Brachygobius nunus habitat. There are very few audio visual data which motivated me last year to work on a water body that consists a beautiful nano fish. Brachygobius nunus are mostly carnivorous and nocturnal which is also an amazing thing to witness very closely in an aquarium.
This aquarium is replicated as much as possible with the original biotope using wild collected proper aquatic plants and floaters from the lake. It was an amazing experience seeing this tiny creatures crossing through dense foliage’s and hardscape. Also the natural shading from the Nymphea pods and water hyacinth roots gave the aquarium a shade for the fishes to feel safe.”
Southeastern Asia & Oceania – sponsored by JBL
Approved by: Greg Martin (ANGFA), Heiko Blessin and Heok Hee Ng (NUS)
BAM: Suoi Cat stream, Quang Dien district, Vietnam, by Nguyen Thi Kim Khoac (Vietnam):
“The 300L blackwater aquarium provides an ideal environment for the fish species Tanichthys micagemmae and Oryzias pectoralis, which are the main highlights of the setup. Along with Trichopsis vittata, they swim gracefully among the branches and roots, creating a highly natural and visually captivating scene.”
We invite you to take part in the upcoming BIOTOPE AQUARIUM Contest!
The BIOTOPE AQUARIUM Contest is the best way to bring together aquarists and scientists in an effort to document and monitor the conditions of aquatic habitats and their inhabitants, water quality and possible introduction of alien invasive species that cause damage to native ecosystems and even to people. Public awareness and active involvement of the aquarists play an important role in contributing to the successful implementation of the biotope mapping worldwide with its main instrument, BAP-Map.
The participation in the contest consists of 2 applications:
1. BIOTOPE IN NATURE (BIN) – the personal biotope exploration done in situ or through extensive online research with the involvement and contribution of other aquarists and scientists. This kind of cooperation allows to create a network of people interested in the conservation of aquatic environments and leads to concrete projects. The bibliography/sitography of the BIN might play a decisive role – being a demonstration of profound research, it can be helpful for other biotope fellows to understand that precise ecosystem.
2. BIOTOPE AQUARIUM MODEL (BAM) – the reproduction of the original aquatic biotope as a closed micro-ecosystem in the aquarium. This is more creative and fun part of the application, as the aquarists are required to show their practical skills and biotope knowledge by putting together the right components, such as water chemistry, substrate, light, filtering system, décor, in combination with the correct aquatic inhabitants in correct proportions – fishes, plants, crustaceans, mollusks – to give fish and plants species a home with appropriate niches for hiding and breeding. The most important thing here is to describe in detail one’s own practical experience with the biotope tank – to share their knowledge with aquarist colleagues.
BIOTOPE AQUARIUM Contest is divided into 8 categories, each one judged by the experts who did aquatic research in that particular region – ichthyologists, biologists, professional aquarists with a deep knowledge of local ecosystems and a vast fieldwork experience. The experts define the final ranking and advise all participants on how to improve their setups to make them as close as possible to the natural biotopes.
The international aquatic companies Aquael, Fluval, JBL, Ocean Nutrition and San Francisco Bay Brand understand how important it is for the aquatic hobby to evolve. They look forward to a positive change and embrace the biotope concept as a top level of the aquarium hobby.
BAP is gearing up for BAC2025 opening the registration on April 20st, 2025. We invite you and all hobbyists that take great pride in creating natural-looking environments in their aquariums to take part at the BIOTOPE AQUARIUM Contest (BAC2026)!