Western Mexico River Biotope Riparium
by Devin Biggs (hydrophyte
) Introduction & Background Tank shot 20 June 2009
The idea for this aquarium display occurred to me during a 2006 graduate studies academic fellowship that I completed in Mexico. A number of students and faculty at my host institution, the University of Guadalajara campus in Autlán, Jalisco
, were involved in research on the nearby Ayuquila River, an aquatic ecosystem that is highly valued for its economic, social and ecological importance. Among the noteworthy features of the Ayuquila River are several species in Family Goodeidae, a Mexico-endemic fish group. One of these, Allodontichthys zonistius
, occurs exclusively in the Ayuquila River and its tributaries. Map of Purificación River watershed
Returning to the specifics of the planted riparium display, the fauna list for this tank actually does not include Ayuquila River species, being representative instead of the fish biota of the Purificación River. This stream’s watershed directly adjoins that of the Ayuquila and the river flows in a southwesterly direction to its mouth on the Pacific Ocean. Curiously, while they are very close to each other, the native fish of the Ayuquila and Purificación rivers are almost entirely distinct: they share only one obligate freshwater species, a poecilid livebearer, Poecilisopsis baenschi
. This contrast is a testament to the geological history of the region and its influences on biological diversity. The rugged mountain ranges of Mexico have isolated many populations of organisms in rivers and other ecosystems, a process that has driven the evolution of thousands of new species.
During early spring of 2008 I took a week-long trip to Autlán with the intention of visiting locations within the Purificación River watershed. I used public transportation to visit four different sites on the river and its tributaries, taking advantage of the area’s prompt and extensive bus services. While at the river access points I did my best to accumulate observations of the aquatic flora and fish fauna of the Purificación, as well as the river’s interactions with local human communities. I also collected four species of native Purificación River fish. Using the required Mexican and US documentation, I brought these live specimens home for use in the biotope display. Icthyological researchers at the University of Guadalajara and the University of Wisconsin-Madison helped me to secure the necessary permits. Mexican and U.S. Researchers Sampling Fish in the Ayuquila River
The idea that I had in mind while planning this display was to emulate a streamside Purificación River habitat. While collecting in the river I noticed that the roots and underwater foliage of emergent aquatic plants along its banks were favored locations for fish and many other aquatic animals. This marginal aquatic flora is characteristic for rivers in this area of Mexico—there are few immersed aquatic plants in rivers here. I am unsure of the particular reasons for this, but it might have to do with the high water hardness and pH values for many such streams—the area's geography is characterized by calcareous rocks—and because they run high and fast with floods during the summer rainy season. After visiting many sites in the area, I found only two true plants growing underwater, Bacopa monnieri
, and an interesting fern for which I have not been able to determine species. Unidentified Fern Species Specifications
A 120 gallon (48” wide X 24” tall X 24” deep) rimless glass aquarium holds the display and is supported by a plywood stand built in a minimalist, contemporary style. Life support equipment includes a 6-lamp, 48-inch HO T5 fixture (Tek Light, Sunlight Supply, Inc.) and a 350 gallon/hour canister filter (XP3, Rena). The filter intake and return are plumbed through two holes in the floor of the tank with PVC bulkheads. Short standpipes rise from each bulkhead and are well-hidden toward the rear of the underwater area. No heater is used in this setup. The room where it is placed is relatively warm and the livebearer fish that inhabit it prosper best in somewhat cooler water (low 70’s degrees Fahrenheit) than many tropical aquarium fish.
Riparium hanging planters and trellis rafts (from Riparium Supply) serve as plant supports for the emergent plants in the display.
I use straight tap water in the display. Water hardness and pH are quite high from this source (~18 GH, ~8.2 pH), but these parameters are close to what I observed at sites in Mexico and the fish and plants live very well. Under Cabinet View Flora
I did not attempt to collect and export/import any live plants while in Mexico because I did not have the required paperwork. However, I imagined that I would be able to locate some of the same plants that I observed on the Purificación River here in the US: many of them seemed similar to plants that I had seen in garden ponds. I did my best to observe and photograph riverbank plants during my outings. Heteranthera sp.
As an additional source of potential plants species for the display I also consulted the book Flora de Manantlán, Vascular Plants of the Sierra De Manantlán Biosphere Reserve
, Vázquez-G., J.A., Cuevas-G., R., Cochrane, T.S. and Iltis, H.H. (1990). Universidad de Guadalajara, which contains a comprehensive list of plants species that have been recorded within and near the Sierra de Manantlán Biosphere Reserve, a large protected area that comprises much of the Purificación River watershed. Botanical researchers at the University of Guadalajara, University of Wisconsin-Madison and other institutions produced this reference in recognition of the areas remarkable plant biodiversity. 21 November 2008
The following list includes almost all of the species that I have used in the display. Note the asterisk codes, which are referenced at the bottom of the list. • Ludwigia peruviana **
• Bacopa monnieri *
‘Baby Tut’ **
• Cuphea aequipetala **
• Cyperus alternifolius
'Gracilis' ** • Eleocharis montevidensis **
• Ruellia brittoniana
(bluebells type) **
• Ruellia brittoniana
‘Katie’ ** • Colocasia fallax ***
sp. … ** • Wedelia trilobata *
• Zephyrathes macrosiphon
*Species that occur in the Purificación River area.
**Species that are similar (i.e., con-generics) to plants that occur in the Purificación River area.
***Species and varieties selected for aquascaping usefulness.
Note that only two of the plants in this list, B. monnieri
and Wedelia trilobata
, are species that I know to occur in the Purificación River. I observed both of these during my trips to the field there. In order to add more diversity and create an engaging aquascape I had to select among other commercially available plants. Some of these were close relatives of plants that grow near the Purificación River, while others simply have growth habits that reinforce the general appearance of the streamside vegetation. The sedge, Eleocharis montevidensis
, with its arching grass-like foliage, was especially useful in this regard. Fauna
The fish in this display are all first generation (F1) offspring of the specimens that I collected in the Purificación watershed. The display currently has about seven individuals of each of these. They were all introduced as small juveniles, but have since grown to adult fish. • Poecilia chica
• Poeciliopsis turneri
• Xenotaenia resolanae
These are three of the four obligate freshwater fish species that occur in the Purificación River. Although I also collected the fourth species, Poeciliopsis baenschi
, I decided against using this one in the display because I anticipated that the fish would breed in the tank—as they have done—and I wanted to avoid the possibility of hybridization between the two Poeciliopsis
The Goodeid, X. resolanae
, is an endemic whose natural distribution is restricted to the Purificación watershed. The Poecilids, P. chica
and P. turneri
, occur in the Purificación and just a few neighboring drainages.
I have considered adding a few additional animals that are available in the aquarium trade and representative of River Purificación fauna. The vampire shrimp, Atya gabonensis
, is native to West Africa, but similar to the large filter-feeding Atya
shrimp in the Purificación. A Sicydium
goby (e.g., S. punctatum
) would be another intriguing addition, representative of the catadromous Sicydium
gobies in the river, and might help to graze algae in the tank. Substrates
As was the case for the live plants, the substrates in this aquarium were selected with the intention of recreating a riverbank environment. To this end, rounded stones of varying sizes were placed in the tank. The largest of these are a product that I acquired from a local supplier “split fieldstone”, which are natural rocks cleaved flat on one side so that they may be easily mortared in place to build walls, hearths and other vertical structures. I acquired a large volume of fine gravel by screening “paving base”, a mixed grade sand and gravel mix used as a pavement underlayment. I took some artistic liberty with the use of manzanita driftwood. One might not often see dead branches protruding directly upward from a riverbed, but this configuration created a pleasing effect in this case. 28 July 2008 23 October 2008 Challenges
I live several miles away from the building where the display is set up, a science education outreach center on the UW-Madison campus. I knew that every trip taken to the display would be expensive and time-consuming, so I designed it to be as low-maintenance as possible. I usually only service it once or twice each week, spending approximately ˝-hour working on the system during each visit. Maintenance tasks include partial water changes, plant fertilization, glass cleaning, equipment checks and plant trimming. 18 February 2009
Overall, I have experienced few serious maintenance challenges with this display. Since most of the plant foliage is above the water’s surface, I have had little trouble with algae. The fish graze the algae turfs on the displays rocks and other substrate surfaces, which also helps in this regard.
Last fall, after the display had been set up for approximately six months, several of the plants had grown tall and leggy, with the effect that the underwater area became dark and shaded. I took the opportunity to perform a partial rescape. I moved some of the rocks about and also changed the vegetative theme. The plants had been dominated by arching forms, especially the sedge Eleocharis montevidensis
, and various lilies, but it changed to an emphasis on tall umbrella sedges (Cyperus
sp.) as background elements and semi woody shrubs (e.g., Ludwigia peruviana
) in the midground. Final Thoughts
Planning, setting up and maintaining this riparium have been fun and educational activities. I hope that other participants in the project have also enjoyed it. Since it is a biotope display, I had to do a good deal of research while assembling the live plants and fish that it holds, an effort that was an especially rich learning experience for me. I especially enjoyed my trips to the field in Mexico where I visited beautiful places within the Purificación River watershed. Acknowledgments
This project was completed with the support of: Science House
the UW-Madison facility that hosted the riparium display The Madison Aquarium Gardeners Club
(MAGC) assisted with financial and organizational support
Members of MAGC also offered instructive input during planning of the display and participated in its setup and maintenance. Filling Tank—Plumbing Test
The following businesses also provided direct support:
Orchids Garden Centre
Sunlight Supply, Inc.
(editor's note: I apologize to hydrophyte and the APC members for the delay in producing this article, work and home issues have been taking a considerable amount of my time - hooha)