9338

• UCREFRP Catalog Number: 9338
• Author: Schler, P. J.
• Title: Colorado Pikeminnow Culture Manual.
• USFW Year: 2001.
• USFW - Doc Type: FY92-37,
• Copyright Material: NO

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This experiment consisted of rearing pikeminnow in stainless steel troughs (4ft x 1ft x 1ft) at two
different water depths (3.5 inches and 7 inches). Growth was similar at both depths, but behavioral
differences were observed. Fish had less fright response in deeper water than in shallower water. In
an earlier trial, greater growth was noted in a circular tank, 3 feet in depth. The greater depth of'
circular tanks should be investigated further.

FOOD STORAGE AND PREPARATION

When feeding live brine shrimp, Artemia, daily hatch-outs were required to maintain a quality
food supply for young pikeminnow fry. Instructions for incubation and hatch-out accompany most
commercial brands of brine shrimp eggs (Artemia cysts). Depending on percent of hatch-out, and
the nutritional value and size of nauplii, there are many different commercial brands available. The
FRH used Argentemia Grade IT (Argent Chemical Laboratories, Redmond, Washington) brine shrimp.
Typical hatch-out time was around 24 hours. Live nauplii should then be siphoned out of the
hatching container (trying to exclude as many unhatched cysts and shell casings as possible) into a
feeding container. Between feedings, live nauplii should be kept refrigerated to reduce their
metabolic rate and preserve their nutritional value.

All commercial diets were stored in a walk-in freezer (100 F) until day of use. All commercial
feeds were used or discarded within a three-month period of manufacturer's milling date. Ideally,
quantities being used should be calculated monthly and appropriate orders then placed to the feed
companies. Shipments of feed typically arrived every four to six weeks.

FEED EVALUATION

Fish feeds used during experiments were analyzed by both private and Colorado Division of
Wildlife laboratories to a make sure manufacturer guarantees for percent of protein, fat, fiber, and
ash were met. The ultimate feed evaluation is how well it does when fed to the fish, i.e. the growth
and condition of the fish.

FEEDING PRACTICES

The feeds and feeding techniques described in this section have produced the best growth and
highest survival among all pikeminnow feeding trials at the (68-700). Nutritional value, particle size,
and palatability detennine the feed fed. The timing offeed changes was based on size of the fish and
growth rates. Many of the recommendations were developed by trial and error and are still in an
improvement phase. Depending upon each individual hatchery's water quality parameters
(temperature, chemistry, flow, etc.) and fish stock (egg source), adjustments will have to be made
independently.

Feeds and Feeding Regime
. At 68-700 F, pikeminnow fry absorb their yolk. sacs in five to seven days and will begin
swimming to the surface. Upon swim-up, initial feeding should begin. Live brine shrimp nauplii,

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