Small-Scale Trout Farming

Raising rainbow trout commercially is a profitable alternative to conventional agriculture that can be practiced with very little land, provided that water conditions in the facility and the care and feeding of the trout are properly maintained.


| September/October 1983



small-trout-in-hand

This Kamloops has lived at Eco-Village for only a few weeks, and will require almost a year's worth of feeding before it's ready for the market.


MOTHER EARTH NEWS STAFF

When most people think of farming, visions of fields of corn or pastures dotted with contented cows probably come to mind. And when those same folks talk about agricultural profitability, the conversation likely tends to turn to bushels per acre, tons of silage, and the continual gambles upon rain and frost. However, when MOTHER's own Rick Compton thinks about farming these days (and he's already been the usual route), his mind dwells upon flows in gallons per minute, pH, oxygen content, and conversion ratios. Why? Because since the first of June 1983, Rick's "flock" has consisted of about 1,700 pounds of rainbow trout (Salmo gairdneri kamloops), which he's raised from fingerlings (130 of them to the pound) in four small man-made ponds at MOTHER's Eco-Village Research Center.

In a few weeks, when the processor arrives to pick up those fish that have reached a mature 14 ounces, we'll receive about $1.85 per pound for trout that cost only 60¢ a pound to raise. What's more, other fish will be sold to Eco-Village anglers at the standard area catch-out pond price of $1.85 per pound. Naturally, it wasn't Rick's sole intent to turn a profit (though it looks as if he'll manage it). Rather, he had hoped to demonstrate, through trout farming, a type of aquaculture that can provide a tidy supplementary income in a small space, or, on a larger scale—if you'll pardon the pun—provide an excellent means of making a living!

Farmed Trout On the Menu

You might be surprised to know that about 95% of the 11,000,000 pounds of rainbow trout eaten in the United States each year is raised commercially. Since 1900, when fish culture began to be recognized as a viable business, many advances have been made in breeding and growing methods, in fact, "commercial" trout are now generally acknowledged to be at least equal (in taste and texture) to their wild counterparts. And of course, without aquaculture—in the form of our hatchery system—the meager productivity of natural waters would have resulted in trout's being a rare and expensive delicacy (if not a nearly extinct species) as a consequence of over-fishing.

Trout farming is most popular along a portion of the spring-fed Snake River in Idaho until very recently, 90% of the trout raised in the U.S. came from that spectacular 32-mile-long stretch—but it's now being practiced successfully in Arkansas, northern Georgia, New Jersey, North Carolina, Pennsylvania, Tennessee, and Washington, as well. There are likely other areas where the required clean, cool (but not too cold), and abundant water is available, however. Indeed, once you have a general knowledge of the necessary conditions, you may discover that your area is "ripe" for an experimental fish farm.

Water Temperature and Oxygen Content for Trout Farming

Rainbow trout (which are usually preferred for intensive growing over the other varieties) are an amazingly hardy breed, but if you're to have the most productive ponds possible, you'll need to provide your fish with the right environment. Once past the fingerling size, rainbows grow most rapidly when the water temperature stays in the 55° to 58°F range. (They can survive down to about 34° or up to around 70°, but their enzymatic systems will be upset, and their growth will halt long before those deadly levels are reached.)

Temperature also influences the amount of oxygen that water can hold, so an overly warm pond imposes a double threat. In fact, water at 39°F can hold about 12.9 parts per million (ppm) at saturation, while at 68°F it can maintain only 9 ppm. Since rainbows begin to become distressed at oxygen levels of below 6 ppm, and will die at 3 ppm, cooler water provides a much greater margin of safety. Furthermore, in a "stair step" pond system like Rick's, if the oxygen level of liquid entering the course is only 9 ppm, there's a much greater chance that the fish in the upper ponds will use so much oxygen that those in the lower pools will suffocate. This problem can be eased by including aeration devices along the way. For example, Rick installed splashboards made from corrugated fiberglass (with holes drilled in them) at the downstream end of each of our ponds, and made sure that the entry line at the top of each tank was angled up at 45 degrees to create splashing. Finally, altitude is yet another factor that comes into play with oxygen content, since the saturation level of water declines about 0.5 ppm for every 1,000 feet above sea level.

robert smith
11/14/2010 7:13:50 PM

I am presently in the process of getting permits to put in a trout pona and am possibly thinking about making it a small commercial operation. We have some small springs and avery small creek and we are at 2000 ft altitude. I am currently getting bids to dig the ponds. Amy suggestions from those more experienced.


art piotrowski
6/24/2009 10:14:32 PM

Great article. I wish I could find out more about fish farming. Thanks.


choclosteve
6/22/2008 7:59:44 PM

I have a small pond earthen pond that I have stocked with tri[pliod rainbows twice @ 100 nine inchers- they grew better than an inch a month until river otters found them. Any body got an otter hound? They're hard to find. Gonna try an electric fence. The steep sides seem to have discouraged the herons, who visit my pond and look from a tree, but don't find a good spot to wade. I worry about osprey and eagles, but have not been found by them yet.


susan_50
12/15/2007 5:20:16 PM

Wow! What a great article. Makes ya wanna go out and fish farm.






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