Paddlefish are filter feeders with the bulk of their diet being made up of zooplankton. It is not usual to catch paddlefish on bait but some old records exist of bait being used for paddlefish. However, today the main method of catching paddlefish is by snagging them.
Depending on the habitat and the time of year, Paddlefish are feeding on different kinds of food. Some Paddlefish are planktivores and insectivores, but most will feed on zooplankton.
Crustacean zooplankton seems to be their most preferred type of food, with Mayfly naiads and water fleas being their favorite prey.
In winter and early summer, Paddlefish mostly feed on Cyclopoids, and during fall and late spring, their favorite prey are Calanoids. In late fall, Paddlefish feeds primarily on Diaptomus silicides.
Because of the way the Paddlefish feed, they also ingest large amounts of aquatic insects. In fact, lots of Paddlefish often actively pursue this type of prey.
Adult Paddlefish can also capture and digest small fish, and it is not uncommon for them to target fish fry schools.
How do Paddlefish Feed?
The Paddlefish are filter feeders. They suck up everything from the water column and filter it through their sieve-like gill rakers, although adult fish don’t keep anything smaller than 0.007 inches long. Smaller fish can retain prey with smaller sizes.
The reason for the smaller prey being absent in the Paddlefish diet is the gill rakers’ spacing, limiting the prey’s size.
Even though Paddlefish feed swimming with their mouths open, they can actively select their preferred food. They often switch between filtration and active selection depending on the size and abundance of their prey.
During the feeding, the position of gill rakers changes from facing back to face outward, forming a sieve that filters all the water that passes through the Paddlefish mouth. The Paddlefish can control the water intake and, therefore, the amount of plankton going through the gill rakers by adjusting the swimming speed and the angle of the rakers.
Paddlefish have poor eyesight but detect their food by the electroreceptors in their rostrums and gill rakers and sensory receptors located in the front part of their bodies. They are able to detect their prey at a distance of about 3.1 – 3.5 inches.
Young Paddlefish feed in a different way than adult fish. They also feed on zooplankton and insects, but only in a selective manner, and they pick the biggest prey available, always targeting individual prey. The reason is that baby Paddlefish are too small to filter feed, and their gill rakers are not yet developed to sieve the water.
The gill rakers become fully functional when young Paddlefish reach around 8.8 – 9.8 inches in size.
When do Paddlefish Feed
Paddlefish can feed at all times of the day and night with few intervals for rest and searching for better feeding grounds, but their preferred time of feeding is at night and early morning.
Spring (from April till mid-June) and fall (from mid-September to November) seasons are feeding peaks for Paddlefish. They continue to feed throughout the winter and summer months, and the feeding starts to cease in March and between late June and the middle of August.
Paddlefish often stop feeding almost entirely between the middle of August and the beginning of September and through the second half of March.
The feeding patterns and the fasting periods are related to water amount and temperature in the rivers where the fish live. The water from melting ice and snow in early spring causes turbulence of sandy bottoms, making it difficult for Paddlefish to filter through. Paddlefish stomachs can fill with sand and silt during that time, leaving very little space for the digestive matter.
Paddlefish usually don’t feed in during the hottest part of the year when the amount of food is too low and won’t cover the exertion of energy needed to obtain it.
How Much Food do Paddlefish Need
In total, the stomach of an adult Paddlefish can contain around 340ml of material, and considering they “swallow” everything that they catch in their gill rakers, sand and detritus often fill their stomachs, sometimes even up to 50% of the stomach volume.
Paddlefish digest their food very slowly and feed only when they can justify exerting energy. Usually, Paddlefish would fill their stomachs to their full capacity before they take a break to digest the food.
What Bait to Use For Paddlefish fishing?
Because Paddlefish eat primarily microscopic food, it is challenging to entice them to bite any bait you may put on your hook.
There are old recordings of anglers that caught Paddlefish in the late 1950s on a hook baited with a minnow, but there are no such recordings since.
The most popular method to catch the Paddlefish is to snag it on the side with a treble hook by trolling or casting and reeling in.
Paddlefish are filter feeders that feed on microscopic food. Their diet is made up of mostly zooplankton but they are also known to feed on insects and even fish fry.