The Orinoco Project

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May 9, 2023
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Perth, Australia
Orinoco Project

Introduction and planning​

The Orinoco River is one of the longest rivers in South America, at 2,250km. 76% of the River is in Venezuela and the remainder is in Colombia. There are four stretches in unequal length: the Upper Orinoco (286 km), Middle Orinoco (805 km), Lower Orinoco (959 km) and the Delta Amacuro (200 km). The River is home to more than 1,000 fish species, some of which are important to the aquarium trade. The three tetra species that I'm going to keep, all native to the Orinoco, are: Paracheirodon axelrodi (cardinal tetra), Hemigrammus rhodostomus (rummy-nose tetra) and Hyphessobrycon sweglesi (red phantom tetra).

The three tetra species are native to the basin and the upper Orinoco respectively. Paracheirodon axelrodi also lives in the Rio Negro basin, which contain blackwater and tannin-induced environments, while there is a separate species of Hemigrammus, discovered in 1986, Hemigrammus bleheri, also native to the Rio Negro basin. Hyphessobrycon sweglesi is native to the Orinoco drainage basin. All of the three native tetra species live in slightly-acidic to neutral water and a slightly different temperature range. The school sizes for the three species in this project are:

Cardinal: 9 (6 existing, 3 new)

Rummy-nose: 8

Red phantom: 7

The aquarium

The aquarium used for the project is a Juwel Lido 200 tank (65cm height, 71cm length, 51cm diameter). According to the Tropical Fish Forums aquarium calculator, in actuality it holds 235 litres (62 US gallons) in size in the same specifications. Modifications can be made for the aquarium with the removal of the space-taking internal filter and silicone that goes with it. It will be replaced with a similar filter that's easy to clean and maintain. The aquarium comes with a cabinet for storage of fish supplies (i.e. fish flakes) and a power plug.

Plants used for the setup include Helanthium tenellum, Sagittaria subulata and Ceratophyllum demersum, the first two which are native to the Orinoco. Some of the plants are fast-growers and some require more light and cO2 than others. Ceratophyllum demersum is a declared pest in Tasmania and New Zealand. However, it is permitted in Western Australia.

Planning before making the project is vital for a good Orinoco biotope. Sketching some designs and ideas for the Juwel Lido 200 and making some changes will help bring the vision of the biotope to life. To recreate the Orinoco's wet and dry season, a submersible pump with an automated timer may be needed to raise and lower the water level. The wet season will involve less water changes and more feedings, and the dry season is the opposite. The optional HeliaLux Spectrum with the SmartControl helps with dimming and the times of the day. This, to be used for the biotope, will help make the intended project more realistic and makes a less stressful environment for the three tetra species. Tetras can be stressed when the lighting is too bright, so the HeliaLux Spectrum and its SmartControl will fix the problem.

The 6 existing Paracheirodon axelrodi have been living with a small group of the aggressive Hasemania nana (silvertip tetra), native to the Sao Francisco basin in Brazil. The tank itself is a 30cm length 45cm height 30cm diameter 10 gallon tank, which is too small for both species. But the 6 Paracheirodon axelrodi need to be moved into the Juwel Lido 200 to reduce the amount of stress they had from Hasemania nana. The Hasemania nana was the first fish to be put in the 10 gallon and the Paracheirodon axelrodi were next. This, however, turned into stressed fish and fin nippers chasing the others. This problem will be eventually solved by separating the two species away from each other, with Paracheirodon axelrodi being moved into the 235 litre tank.

All the things mentioned are important for the Orinoco project and its educational value. The goal of the aquarium project is to educate and share important information about the Orinoco River and its unique ecosystems. Research is very important in making a biotope, learning about the fishes' natural habitat and how to recreate it accurately and realistically is key. Simulating the wet and dry seasons, for example, can be hard to maintain properly, but it will help benefit the tetras' wellbeing. Just remember to do it gradually in order to reduce stress.

I'll have to wait a long time until mum and dad give the green light on the project. Let's hope my current cardinal tetras don't die before the project begins.

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