Aquarium & Tropical Fish Site
November '11

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November '11 - Goldfish and Koi: the RESPONSIBLE way to keep them!

Year in, year out, we're already well into the 21st century and, despite all the accumulated human knowledge and all the information readily available nowadays to the common citizen, it's frustrating to see the enormous number of people who still keep ornamental fish in totally inadequate conditions. This is particularly frequent and worrying with goldfish and koi fish, species that have been kept in captivity for millennia, since the inception of fishkeeping. Maybe for this very reason they are among the greatest victims of myths that still plague the hobby, such as "fish grow to the size of the tank" (?!). The fact that the media in general perpetuates the image of the "goldfish in a fish bowl" as an icon of fishkeeping doesn't help at all to dispell the myths. So let's make another effort on this site towards enlightment and general awareness:

Goldfish
  • All varieties of goldfish reach on average 15 to 25 cm (potentially growing past 30 cm) and have a natural life expectancy above 20 years (potentially living beyond 40 years).
  • There's no such thing as "small goldfish", only young goldfish: they're sold in shops at a few months up to a year of age.
  • Kept responsibly, all of them will reach the cited size and age, otherwise they will suffer atrophy and have their life spans severely shortened (just a few years) if kept irresponsibly.
  • Goldfish are fish meant to be kept in groups, in aquariums or mini-ponds with hundreds of liters!
Koi
  • All varieties of koi reach on average 60 to 80 cm (potentially growing past 100 cm) and have a natural life expectancy above 40 years (potentially living beyond 100 years!!!).
  • There's no such thing as "small koi", only young koi: they're sold in shops at a few months up to a year of age.
  • Kept responsibly, all of them will reach the cited size and age, otherwise they will suffer atrophy and have their life spans severely shortened (just a few years) if kept irresponsibly.
  • Koi are fish meant to be kept in groups, in ornamental ponds with thousands of liters!

Hence, if you know people who are keeping goldfish in inadequate conditions (aquariums smaller than 100 L) ou koi in inadequate conditions (aquariums or ponds smaller than 1000 L) do your part to free them from the "Dark Ages" of fishkeeping and point them to this page or to any other on the web, where they may have a chance to grow awareness and take responsibility over a pet that may accompany them for the better part of their lives!

For November, we feature 2 good examples of how to CORRECTLY keep goldfish and koi:

11_Goldfish_Aquarium_1.jpg (40kb)

Marcio Tanque's 375 L Goldfish Aquarium (Brazil)

This is a goldfish aquarium that's completing 8 months. It measures 150x50x50 cm, and was set up very economically. The lighting is an adaptation I made with a 120 cm (40 W) common dayhlight tube, since there's only a bundle of cabomba to give a more natural impression of the aquarium. The filter was improvised, using a 20 L mineral water gallon, where I put crushed ceramics for the water to trickle through like a water bed, which then falls into a PVC box where I put activated carbon, then down to a second, cut gallon of mineral water where the mechanical filtration goes using acrylon over crushed ceramics, and through ceramic tubes forming a biological filter. This aquarium has no heater, since it's unnecessary in where I live for goldfish only tanks. Partial water changes are made every week since the goldfish produce a lot of waste, but the maintenance is quite simple.

11_Goldfish_Aquarium_2.jpg (57kb)

11_Koi_Pond_1.jpg (106kb)

Mizuho Tahara's 30,000 L Ornamental Koi Pond (Brazil)

My ornamental pond holds about 30,000 L of water, with a depth of 1.7 m to 2.2 m. There's a ~1,000 L decanter and a 9,000 L filter. I redid it in 1992 with the gardener who knows the most about nishikigoi ponds around here (Mr. Sumida) and in the following 15 years I only had to clean the filter twice. The water remains very clean and hosts dozens of koi around 60 to 80 cm. There's one specimen with about 120 cm!

11_Koi_Pond_2.jpg (50kb)

If you'd like to submit an aquarium for Tank of the Month, just contact me.

Photos taken by their respective authors and displayed here with their permission.



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