After centuries of debating the effects of nurture vs. nature and how they influence an organism’s behavior, scientists have come to an understanding of a certain gray area where genetics and environmental factors work in tandem. To further enforce the matter, an animal’s environment influences its genes through natural selection. Malawi cichlids, for instance, tend to be more aggressive from living in environments with heavy competition and limited resources. Aquarists can harness the power of this knowledge when selecting new tank inhabitants with preferred temperaments. This week, we will focus on fish that exemplify one of the most commonly sought behavioral characteristics, and the corresponding environments that led them there. Found swimming through dark, slow moving tributaries with leaf litter, sand, and heavy wooden debris are many peaceful, and easy going freshwater species. Common to these habitats in South America are Rineloricaria lanceolata, Panaqolus changae, and Hemigrammus rubrostriatus.
Known as one of the most peaceful catfish readily available in the hobby, R. lanceolata, is slow-moving, yet are regarded as relatively outgoing when settled in biotope tanks. Also known as “High Dorsal Whiptail Catfish”, these friendly cats can be easily housed in community tanks with many Apistos, Cories, other peaceful Catfish, or any other peaceful community fish, however, any territorial or boisterous tankmates may outcompete these sluggish fellows. Found in slow moving tributaries of Peru and Brazil, captive settings should include sandy substrate, dried leaves, twisted branches, water-worn rocks, caves, dense vegetation, and low light. Reaching about 4 inches in length at maturity, these catfish can be spotted hiding along tank bottoms with mottled-tan bodies, long “whip-tails”, an extended sail-like dorsal fin, and bulging eyes atop flattened heads. Omnivorous eaters, these whiptail cats are easy to feed, as they will accept high quality sinking dried foods supplemented by prepared vegetal matter like blanched spinach or spirulina, and live and frozen fare like bloodworm or daphnia. Ideal water conditions include temperatures between 77 and 82°F, pH of 6.0 to 8.0, and hardness of 35 to 143 ppm.
Another South American Catfish, P. changae, is a peaceful, wood-eating beauty. Rare in the aquarist hobby, this catfish reaches about 4 inches at maturity, and exhibits beautiful dark tiger striping over a tan body. Also known as the “Iquitos Tiger Pleco”, it is found amongst woody debris and leaf litter in the Upper Amazon basin of Peru. Wooded tank setups are a must, with tangles and driftwood logs of many types for nibbling. Aquatic plants are unnecessary, and may end up getting eaten. In captivity, this diet can be padded with other vegetarian foods like algae wafers, zucchini, and potatoes. Ideal for many community tanks, these catfish are best kept alongside others with similar quiet and less-boisterous community fish. These Tiger Catfish can become territorial with conspecifics, though when kept in larger tanks with many hiding places, groups can coexist peacefully. Iquitos Tiger Plecos do best in tanks with water temperatures between 77 and 84°F, and pH between 5.0 and 7.0.
A perfect compliment to these South American Catfish, H. rubrostriatus exemplifies the peaceful community fish endemic to these slow-moving tributary environments. More commonly referred to as “Red Stripe Tetras”, these shoaling fish reach about 2 inches in length and exhibit a bright red horizontal stripe down the sides of their bodies ending in a bold black spot on their caudal fins. A schoaling species, these fish are best kept in groups greater than 10, though 6 or more will do in a pinch, to bring out the best in coloration and personality. Found in the slow-moving tributaries of Colombia, these tetras are omnivorous munching anything they can get their small mouths around. In captivity, they readily accept dried flakes and granules supplemented by small live and frozen fare. Tank setups should include river sand, driftwood branches, leaf litter, and low light. Waters should be maintained with temperatures between 72 and 79°F, pH of 5.5 to 7.0, and hardness between 21 and 85 ppm.
We are all products of our environments, and this extends to our fish tanks as well. When looking for new tank inhabitants with particular traits, imagine where these traits might be found, and hit the books, or pick up the phone to chat with one of our Wet Spot experts! The possibilities may surprise you!