I also chose to use a central air supply with 20 gallon aquariums for rearing young fish. I limited the tanks to 25 watt heaters, covered them tightly and insulated with styrofoam. They are able to keep about a 18'F increase from room temperature. I run another three larger aquariums with the air pump all for just 32 watts. It is still too expensive to break even for the fish I keep.
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Hybridfish7 gave some great advice. Make the most of your resources! Start modestly and work towards greater ambitions.
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You may enjoy the challenge of trying the aquarium hobby as a business, but there are less challenging buisnesses to try. Keeping a balanced ledger for a garden for instance.
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Consider two interesting fish you may enjoy keeping:
1.) Neolamprologus beusheri "gombi" - A pair may spawn three times per year laying perhaps a dozen eggs each time and producing half that many fry which will take a full year to raise to the size necessary to sell for maybe $30 each. This interesting and expensive fish will never return a profit for most hobbyists. Hence their scarcity.
2.) Mickey Mouse platties on the other hand might net a profit. Kids love them.
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I made money on sunset mickeys, but the beuscheri were more fun.
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You are considering Plecos and Corys, why? Do you love these fish or are they strictly a buisness decision? Maybe give C. pantanalensis a try?
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When your total sales meet the net capital expense you'll have a sence of accomplishment but you will not truely be at the break-even point unless your in the black on operating expenses as well. Food, water, electricity, time... they are all expenses which should each have metrics past present and future.
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What memories do you hope to have in ten years? A thriving business? Will you keep a balanced ledger that long?
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I run my garden as a for profit venture and it's rewarding in its way. Both I and my fish can eat the fruits of my labor. Initially the plan was to use grocery savings to offset the cost of my aquarium hobby, however a road was laid before me which became an obsession. Currently, the garden does return a net savings of about $1.40/sq.ft/year. About $400 last year. So what!? That's less than two shifts of overtime pay at work.
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Yes, I've been down the road. It is fun. It's a great way to learn a buisness. Only be mindful that you'll likely never see your first true penney in the black.
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I keep a bait fish few would find interesting. In ten years I hope to have the memory of having bred them. An accomplishment. But I do it not for the money, nor for the fame, but simply because God has given them to me for the joy of keeping them.
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Best wishes!