How to Stock a Pond or Lake With Trout (Updated)

Highly valuable as a sport and food fish, trout are well-loved all across the temperate zones of the Northern Hemisphere. These beautiful fish, which are known for being fine table-fare, are extremely rewarding to grow and catch. There’s nothing quite like reeling in a feisty trout on the line, let alone sharing its fresh, nutritious meat with family and friends!

Pond owners in northern regions gravitate toward trout as a desirable stocking fish for a number of reasons. Firstly, trout can readily adapt to cool temperatures and can thrive on a diet of nutritionally balanced fish feeds. Secondly, their cultivation can turn a profit after just a single year of growth. Given conservative production costs and a desirable survival rate, pond-grown trout can save you a lot of money in terms of acquiring quality and freshly harvested protein.

Moreover, the joys of simply watching these fish grow and knowing they can sustain you and your family are well worth the effort. A trout pond will have you wanting to stay active and appreciate the outdoors in the best way possible. Growing trout can shape your relationship with your community as you would be ensuring the provision of healthy, clean, and fresh food, while opening up opportunities for safe, family fishing in your very own dugout.

Popular Types of Trout for Ponds

1) Brook trout (Salvelinus fontinalis)

Native to eastern North America, brook trout comes in several ecological forms and hybrids. Wild, sea-run types and those found in lakes tend to be the largest among their kind. Those that occupy smaller freshwater systems have generalized diets and grow into easily manageable sizes at maturity. Hybrids between this species and its closest relatives are frequently used for stocking lakes and ponds. These include splake (S. fontinalis x S. namaycush) and tiger trout (S. fontinalis x S. trutta).

Brook trout are distinguished by their deep brown-green color with lighter marbling around their flanks. Their bodies are liberally marked with red and yellow dots. In the wild, these fish favor all life stages of both terrestrial and aquatic insects, freshwater invertebrates, small fish, and amphibians. They are now intensively grown as a food fish and to meet angling demands. They can thrive in semi-intensive, flow-through tank systems where they are fed with specialized pellets.

2) Rainbow trout (Oncorhynchus mykiss)

One of the most social among the trout species, and therefore able to thrive in higher densities, rainbow trout are a frequent favorite for pond stocking. With ancestral populations hailing from the Pacific, this species is now found all throughout North America. It is considered a popular aquaculture fish as it is hardy, fast-growing, and can thrive on a diet of fish feeds.

The rainbow trout is known best for its iridescent coloration and for being a tough fighter on the line. Though it is a cold-water fish, it is fairly tolerant of mildly warm conditions. It can grow quite large in the wild, with mature specimens reaching a full length of 20 – 30 inches (51 – 76 cm) long. Artificial propagation of fry has ushered their introduction into many non-native freshwater systems as a sport fish. Their commercial cultivation has led to increasing global demand.

3) Brown trout (Salmo trutta)

Originally from Europe, brown trout have now been introduced into many freshwater systems across the globe. This sportfish tends to be the most likely among the popular trout species to persist in warmer conditions. They can reportedly survive in temperatures of up to 80˚F (26˚C), though cooler water would undoubtedly be optimal for their cultivation.

Now commercially cultured to meet food demands and for stocking in both private pond and public lake systems, brown trout are notably hardy. They are also known for being quite challenging to catch due to their shy nature. These fish are distinguished by their slender, brown bodies which are attractively speckled with dark brown and orange spots. They are opportunistic eaters that favor feeding on insects on the water’s surface. For this reason, they are often targeted by fly fishers.  

Vital Considerations

1) Water temperature

As trout are cold-water fish, the water temperature can significantly affect their survival and growth rates. Temperatures above 70˚F (21˚C) can be lethal for both fry and adults, which is why stocking dates must be timed perfectly. A water temperature range of about 45 – 65˚F (7.2 – 18.3 ˚C) is generally recommended for trout cultivation. Some species, such as rainbow trout and brown trout, are capable of tolerating warmer temperatures (~65 – 75˚F or 18 – 23˚C). However, their survival rate would be severely compromised by prolonged exposure.

2) Dissolved oxygen levels

A high dissolved oxygen concentration is essential to rearing quality trout. The lowest possible saturation level for trout culture is 5 ppm. Nonetheless, anything below 6 ppm may be considered dangerous and can leave you with hardly any fish to harvest at the end of a season. You should always aim to maintain oxygen saturation levels at 80 – 100 percent.

This parameter must be measured periodically and any significant drop should be corrected in a timely manner to prevent undue stress on the fish. A high DO level is absolutely crucial during the stocking period, but note that subsequent overcrowding, temperature increases, or decomposition rates may cause this to plummet.

3) Pond size and depth

Trout can be reared in ponds of just about any size as long as they are stocked in the appropriate densities. Of course, it follows that larger and deeper ponds would have a greater capacity for trout and are less likely to have fluctuating pond parameters.

Generally, trout ponds should be 8 – 12 feet (2.4 – 3.6 meters) deep so that the fish can retreat to the cooler pond bottom whenever surface temperatures increase. A greater depth may be vital in cooler areas where the pond surface may freeze over completely during winter. If the water flow is consistent, a shallower depth may suffice.

4) Species selection

The trout species you decide to stock would depend on your water parameters and on your intentions for cultivating trout. Rainbow trout is perhaps the most common choice for heavily stocked ponds due to its tolerance for crowding. Its catchability lies somewhere in between that of brown trout and brook trout. It is also known for being quite hardy, with bodies that are less prone to being damaged by handling.

Brook trout is often the fish of choice for cooler areas, particularly if it is primarily stocked to later be fished by anglers of all levels. Conversely, brown trout is usually stocked in areas that have slightly warmer summer temperatures and for sport fishers that are willing to wait for a good catch. Compared to rainbow and brook trout, it is also more likely to persist in stagnant ponds.

Regardless of the species they culture, most commercial trout hatcheries will normally produce triploid fry. This means that the fish are infertile and therefore unable to reproduce in the wild. Their infertility considerably reduces the risk of negative impacts on wild fish populations. It makes it impossible for the introduced fingerlings to eventually have self-sustaining populations.

Timetable for Stocking Trout

Regardless of the species you intend to stock, you should aim to introduce your trout into the pond or lake system when ambient conditions are mild and stable. In artificial pond systems, stocking may be done throughout the year. For naturalized pond systems, you will have to consider the impact of either markedly cool winters or warm summers on your fish. In temperate zones, this means that spring or early fall are the most ideal times for pond stocking.

In cooler regions where summer water temperatures rarely exceed 65˚F (18˚C), trout can safely be stocked in spring. In slightly warmer regions, early fall would be the best time to stock fingerlings as they will have had several months to grow in cool water prior to the following summer. Depending on the size and stocking density of the fingerlings, some fall-stocked trout may be ready for harvest in spring. Fingerlings that are stocked in spring may be ready for harvest come fall.

Stocking Plan for Trout

The stocking density for trout would depend on the volume of your pond, the size of the fingerlings, the availability of natural food or budget for fish feeds, and pond fertility. Unfertilized ponds with natural vegetation may accommodate anywhere from 200 – 500 fingerlings per acre. If larger sizes (e.g. 8 – 9 ounces) are desired within a shorter time frame, conservative stocking densities are recommended. Fingerlings tend to grow at a rate of about 1 inch (2.5 cm) per month in natural pond systems. To harvest larger sizes, you will need to either stock older fingerlings or delay harvesting them.

In fed ponds, fish tend to grow at a quicker pace and can be stocked in higher densities. Note that overfeeding and overstocking may compromise the health of the pond system. Additionally, an intensive density may prevent your trout from reaching desirable lengths, especially if they are not intermittently harvested. Anywhere from 2,000 – 4,000 fingerlings per acre may be stocked in consistently fed ponds. Aim to harvest your trout completely, and within a timeframe of 1 – 3 years, prior to restocking a new batch.

For natural lakes, conservative stocking densities are best as you must aim to introduce just enough trout to meet the demands of recreational fishers. Stocking too many fingerlings may negatively impact the food chain, especially if the stocked species are non-native. Large lake ecosystems are less likely to be disrupted by the introduction of trout fingerlings or juveniles. Regardless, it would be prudent to stick to species that are native to the area. Base stocking rates on yearly catch data and fishing demands.

How To Introduce Trout Fingerlings Into a Pond

Depending on your state’s legislation and on your personal preferences, the fingerlings you purchase will range from 3 – 7 inches (7.6 – 18 cm) on average. Make sure you select a reputable supplier that can guarantee the health of your purchased fish. They should also be free of potentially contagious viruses and should be robust enough to withstand transportation. Take extra care whenever you handle the oxygenated bags or tanks of fish, preventing them from sloshing about unnecessarily. For small fingerlings, do not open the bags until they have been “tempered” and are ready to be released. Note that tempering trout does not guarantee their survival in warm water temperatures. 

Tempering your small fingerlings basically means allowing them to slowly become acclimated to the conditions of your pond. The minimal length of time for this part of the stocking process is approximately 20 minutes. Float the bags of fish in a sheltered or cool area of the pond. This will slowly alter the water temperature in the bag, allowing it to be equal to that of the pond. Once the 20 minutes are up, you can open the bags at water level and ensure that the fish can calmly swim out.

If the larger-sized fingerlings are delivered to the lake or pond in a tank, the pond water should gradually be introduced into it. This should slowly allow the temperature and other water parameters to equalize in the tank so that the fingerlings will not experience thermal shock once they are introduced into the actual pond/lake system. Hatcheries may deliver the fish in trucks where the water temperature has already been adjusted to that of the lake. Well-adjusted fingerlings will swim deeper into their new environment and remain fairly energetic.

Mixing Fish Species and Sizes

In natural ponds, trout can be mixed with other cool-water species, including other types of trout. If larger species are already present in the pond, they may consume a fair number of trout fingerlings. This is more likely to occur if natural food sources are scarce or if fish feeds are not regularly provided.

Larger trout are also prone to consuming fingerlings of their congeners or conspecifics. This is particularly true with brown trout, which has been shown to have cannibalistic tendencies. Incompatibilities between species and fish of various sizes can be minimized by having a diversely structured pond or lake system with many places for refuge.

Your stocking plan and selected species would have more to do with your intentions for your pond. Fish that share the same ambient requirements and are native to your area can definitely be mixed and matched with the intention of having a diverse, fishing pond. In contrast, a pond that is meant to cultivate semi-intensive to intensive trout densities may be more productive and profitable if a single species and uniform sizes are used.