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FW Stocking Guide

PostPosted: Sat Nov 29, 2008 6:45 pm
by Crazygar
Beginners Stocking Guide Freshwater
by: Kieron Dodds (KDodds)

I just added a link to my stocking guide on the Salt Water side, but it was based on a Fresh Water guide from a few years back. So I thought I would share the Fresh Water guide as well. While no stocking guide is ever going to be perfect, I've been working on something that takes more into account than the length of the fish. Please use this as a guide ONLY, not a set of RULES. There is no substitute for the knowledge of the experienced aquarist. When in doubt, ask questions and get at least two, preferably three, opinions from experienced people who are NOT trying to sell you something.

Alternative Stocking Rules for Freshwater Aquariums

1. You may not have any fish that is more than one half the length of your tank's shortest side at adult size. It must also be less than or equal to one quarter of the length your tank's longest side.
(Reasons: Any given fish must have enough elbow room to move around. Larger fish put out more waste than smaller fish when measured in a linear fashion. Only Adult sizes are considered here because juveniles need both "room to grow" and, since many juveniles like to hide, room for them to be comfortable in their surroundings.)

2. Measure the length and width of your tank and multiply them. Then, divide by 13. This is the maximum number of inches in fish you can keep at adult size. (Reasons: Why not gallons? Well first, comparing linear lengths of fish to volume of tank is comparing apples and oranges. But, it goes deeper than that. While the volume of water in a given tank is important in diluting the nutrients/waste, surface are is likely more important for gas exchange. Also, fish do not swim vertically, they orient themselves to gravity and swim horizontally, another reason why Surface Area is far more important than Volume.)

3. Multiply the adult size of each fish by the following depending on species: (Reasons: Herbivores put out less waste than omnivores put out less waste than carnivores. Slow species generally have slower metabolisms than fast species, thus putting out less waste. Also, carnivorous species tend to be more "aggressive" towards tank mates, requiring more space.)

    Slow, Herbivore: 0.75
    Slow, Omnivore: 1.00
    Slow, Carnivore: 1.25
    Fast, Herbivore: 1.25
    Fast, Omnivore: 1.50
    Fast, Carnivore: 1.75

4. Add all of the adult fish lengths together for each individual fish, your number may never exceed the number you get in step 2. In addition to being slightly more sound than the 1" rule, these rules force inexperienced aquarists into thinking and researching. Using the above rules, see the examples below:

Assume that a Koi reaches 36". You would need a 72" x 144" x 72" aquarium at a minimum to house Koi. That's approximately 3200 gallons, in which you could keep 17 Koi (fast, herbivore 36" becomes 45"). Which is not a bad setup for these extremely large fish.
Assume than an Oscar reaches 14" (remember 14 x 1.75 = 24.5). You would need a tank at least 28"x56"x28", which would be about 190 gallons, in which you could keep a maximum of 5 Oscars. Still an excellent set-up.
Assume a Neon reaches 1.5". The minimum tank size would be 3" x 6" x 3". However, since a Neon is a Fast, Omnivorous fish, the 1.38 stocking capacity of this hypothetical 1 quart tank is already too small. You would need a tank at least 5" x 6" x 3", which is more like 50 ounces, somewhere between a quart and a half gallon. Still, if you see below about the rules of keeping communities of fish, you would require enough capacity to keep 6 Neons. This would mean a tank more along the lines of 10" x 17" x 10" at a minimum, or about 7.3 gallons.

Choosing Fish for Freshwater Community Aquariums

1. Pick a fish you must have. (Reasons: Everyone knows at least one species that they want to keep. Just imagine throwing each one out, one by one, until there is only one species left, that's your "Pick" fish. There must be a starting point for this to work, so this is as good as any.)

2. No other fish may be more than +/- 2" of that fish's adult size. (Reasons: While it is certainly possible to mix fish of greater/lesser size, it is much easier for the beginner to adhere to this rule to minimize predation and bullying.)

3. No fish may deviate more than +/- 0.2 in preference on the pH scale. (Reasons: Most fish tend to do better when kept in their natural water conditions.)

4. No fish may deviate more than +/- 2ºF in temperature preference. (Reasons: see above.)

5. No fish may deviate more than +/- 1 points in the speed/habit scale below: (Reasons: Fish are not ornaments, they will interact with one another. Shy, retiring species may be bullied by more aggressive, outgoing species.)

    Slow/placid = 0
    Slow/normal = 1
    Slow/aggressive = 2
    Normal/placid = 1
    Normal/normal = 2
    Normal/aggressive = 3
    Fast/placid = 2
    Fast/normal = 3
    Fast/aggressive = 4

6. Individual species should be kept according to habit:

Species which are aggressive towards their own kind should be kept singly, with no other fish that mightseem like the same species because of Genus or outward appearance.
Schooling species should be kept in groups of 6 or more. (Reasons: For much the same reasons as temperature and pH requirements, fish seem to do better in natural circumstances.)
7. The tank should be as closely divided as possible according to the following:

    1/6 of tank occupants should be bottom dwelling.
    1/2 of the tank occupants should be midwater dwellers.
    1/3 of the tank occupants should be top dwellers.
(Reasons: Even non-territorial fish need some elbow room. Providing a variety of habitat types ensures that each species has enough room in their "preferred space". Bottom dwelling species will rarely venture above the bottom third or quarter of the tank which will, most likely, have a lot of space already taken up by plants/decorations. Top dwelling species exhibit the same behavior in reverse but have an advantage in that plats and decorations close to the surface are more likely to be sparse or non-existent. Midwater dwellers will generally use one-half to two-thirds of a tank's vertical height, giving them more space simply out of habit.).