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July 20, 2012

 Summer has arrived and it’s been quite sunny and warm here in Portland. It is much too hot for my tastes, but I suppose I’m more of a temperate fish than a tropical one. I’ve been considering what to write about in my newsletter and found inspiration in my love of air conditioning – subtropical aquaria.

Setting up a cool water aquarium isn’t much different from a tropical setup. The temperature should ideally be kept between 68-74° Fahrenheit year round. The temperature can be allowed to decrease slightly during winter depending upon the tolerance of your livestock, but a wide-range adjustable heater is necessary if the location of your aquarium often drops below 65°. It is best to keep your subtropical aquarium in a cool part of the house to avoid the necessity of water cooling methods during the summer. The vast majority of our coolwater fish occur in mountain streams and rivers in the wild; they enjoy high currents and oxygenation and benefit from overfiltration, powerheads, airstones, or any combination thereof.

A great number of hobbyists recognize the Danio genus as a wonderful source of cool water fish. I’m quite fond of Brachydanio cf. keeri “Hikari Yellow Danio”, the males of which sport an iridescent yellow-green sheen, as well as Danio sp. "Kyathit" “Burmese Kyathit Danio” with its red fins and blue and yellow mottled stripes. There are numerous other lovely Danios to choose from as well, but one of my personal favorites is Danio pathirana “Pathiran’s Danio”. These are beautiful 3” insectivorous fish, slightly more full-bodied than other Danios with a center line cut vertically by brilliant blue and gold bands. They are somewhat more sedentary and enjoy slightly warmer water than many other Danios, though this is only by a few degrees. Their ideal temperature range is 69-78° F with a preference for soft, acidic water with a decent current. These fish originate in the Nilwala River watershed and are considered endangered in the wild due to cultivation of the land around the watershed.

Danio pathirana

Many species of Corydoras are well suited to subtropical aquaria. C. paleatus “Salt and Pepper Cory” and C. duplicareus “Duplicate Cory” are both happy in a temperature range of 68-74° F. However, I’ve currently been taken by another cool water species hailing from Rio Negro and Rio Uaupes in Brazil: Corydoras adolfoi, “Adolfo’s Cory”. Adolfo’s Cory looks very similar to the Duplicate Cory, featuring the same black caudal edge stripe and facial mask as well as a brilliant orange head cap just before the caudal fin; the greatest difference between the two is that Adolfo’s Cory has a thinner black stripe along its caudal edge than the Duplicate Cory. This species grows to a length of 2.4”, enjoys 68-78°F soft acidic water between pH 5.6 and pH 7.0, and has a preference for blackwater conditions, though the latter is not necessary. Adolfo’s Cory enjoys dense planting around the edges of its aquarium home and soft, sandy substrate that will not damage their delicate barbels which are primarily used to scavenge for sunken food particles.

Corydoras adolfoi

There are many species of ‘Hillstream’ or ‘Butterfly’ loaches perfectly suited to subtropical aquaria with high water flow and oxygenation. These fish have very similar requirements to each other and the vast majority of them prefer water temperatures from 68-75°F. Additionally, the Panda Loach, Protomyzon pachychilus, also enjoys a subtropical habitat. I’ve chosen to focus on Sewellia cf. breventralis “Porcupine Hillstream Loach”,one of our newest acquisitions from the Hillstream loach group. These particular fish are not yet fully described in the hobby, but are believed to originate in the Hue province of Vietnam in fast-flowing softwater tributaries and headwaters. The Porcupine Hillstream Loach sports a mottled, snakeskin-like pattern, reaches 2.4” and enjoys a diet of algae and biofilm scraped from smooth river rocks, making them a perfect algae eater for the subtropical aquarium.

Another interesting group of fish entirely suited to cool water aquariums is the Rhinogobius genus of gobies, preferring 68-78°F water. I’ve regularly seen R. duospilus “Flame Cheek Goby”, R. leavelli “Yellow Fin Goby”, R. sp. “Flower Goby”, and R. zhoui “Scarlet Goby” amongst our stock. The Scarlet Goby is a rare and stunningly colorful specimen: Its centerline is vertically transversed by several scarlet-red stripes and its red fins are bordered with brilliant blue-white. This fish is endemic to the highest streams of Lianhua Mountain, China. High currents and clean water are typical of its environment, as well as submerged rock substrates. Scarlet Gobies are active fish with large personalities – they are non-aggressively territorial (this is unlikely to lead to injury) and make quite a show flaring to intimidate their fellow gobies away from their home turf.

Rhinogobius zhoui

Last week, Anthony wrote about the beautiful Tanichthys albonubes "White Cloud Mountain Minnow" and its relatives and color morphs. This genus is definitely suitable for a subtropical aquarium, as well as some barbs such as Puntius semifasciolatus “Gold Barb”, and a few tetras, including the wonderful green and red Aphyocharax rathbuni “Green Fire Tetra.”   Unfortunately, I don’t have any more space to talk about these beautiful schooling fish.

Thank you for reading and I hope you found my newsletter interesting and informative. I’ve enjoyed helping you all with your questions and orders over the past week. Anthony will be back on Monday!

Jessica Supalla