When people envision carp, they think of a single species, but Iowa waters is home to a wide variety of bottom-feeding fish. Some of which are harmless forage species and others that could turn a boat upside down if provoked. What most anglers do is lump all of these fish into the “mud sucker” category.
While it will certainly keep you on target with the basics, it restricts your knowledge of local angling opportunity and overall ecology. Knowing which type of carp you’re dealing with are important, as all species have their own characteristics. Some are considered ecological pests; others is prized as trophies.
That makes a difference to how you will fish for them, such as bait and locations you use. It also affects whether or not you will release your catch. And it reveals the differences in feeding habits, scale patterns, etc., that define these tough fish.
Five Common Carp Species Found in Iowa
1. Common Carp
The first invader to Iowa waterways was common carp. They were originally brought into the state for food and to remove aquatic plants in the nineteenth century. These fish has become a mainstay in most of the state’s slow moving rivers and lakes.
When environmental conditions are right they can reach a large size. Some reaches over 50 pounds in weight. Common carp is easily identifiable with a deeply forked tail and irregular, very large scales.
Unlike our native species, they also lacks barbels around their mouth. To feed, these fish suck in insects, plant matter and other sediment using a mouth that can extends. While doing so, they stir up the mucky stuff on the bottom of lake.
Cloudy water follows. Often people assume it’s an indication of bad water quality. Nope.
It is just carp activity.
2. Crucian Carp
Common carp are not as large than crucians. Crucians are far more durable than typical carp.
In appearance they resembles miniature common carp with deep bodies and silvery scales that glitter in sunlight. In fact, you can appreciate those subtle differences in scale patterns and feeding habits that define these fish. A critical biological oddity of crucians makes them able to survive harsh environments.
Their ability to live in severely oxygen-depleted or cold water are due to intestinal respiration. Basically some populations literally breathe through their guts. Other fish perish while crucians survives.
But this resiliency maintains important members of the food chain, like the crucian carp in temporary wetlands and small ponds. Crucilian carp do not exceed one pound in size. They rarely reach a pound.
Because of this, they don’t fall prey much to sport fisher. They also are an important component of the food chain, providing forage for bigger predators. And because they can live in marginal habitats, they do.
Almost without exception, you’ll find them even in water bodies that appear unwelcoming for life.
3. Wild Goldfish
What throws a lot of guys off are wild goldfish. No, these aren’t the colorful bowl pets you buy at the pet store.
These are feral offspring from those fish that either escape into the wild or is set free by someone. Usually, they look like common carp. But generally, their scales is smoother and body more streamlined.
Wild goldfish tend to hybridize with common carp in Iowa too which makes it hard to untangle the genetic blurring. The presence of feral goldfish indicates areas with high human activity, such as parks or residential ponds. You’ll see a lot around ponds in parks and neighborhoods.
These guys breeds like crazy. That means in small waters, they can overrun very fast. While goldfish are not an invasive species in the same legal sense as common carp, they do out-compete our native sunfish and minnows for food and other resources.
Knowing where they are will help anglers become more aware of the pressure that ecosystems face. This pressure comes from good intentions gone wrong, also known as releases.
4. Silver Carp
The most disruptive of new fish in Iowa waters would of been silver carp.
Originally introduced into Iowa waters as an algae control and aquaculture fish, these fish escaped and spread quickly. Silver carp don’t have barbels nor do they has teeth. When swimming, they swim with their mouth open filtering debris and plankton out of the water column.
They are fast growing due to this type of feeding behavior. They often outcompetes native baitfish. However, the problem is how they react if they are startled from above by things like boat motors.
When startled, silver carp will jump high into the air to get away from any loud sound. Sometimes they hits anglers or boaters in the process. Because of that, they are dangerous to humans.
On top of that, they are an ecological hazard too. Iowa alone has spent millions trying to stop them from spreading further. They are concentrated primarily in the Missouri and Mississippi river basins.
Their being there alters the way a fishery work. Often this results in the decline of other species due to food competition.
5. Black Carp
Most anglers don’t see black carp.
That’s because most anglers don’t catch them. However, management agencies has serious concerns with this species. Also known by some as grass carp (but not the same species), black carp are a specialized snail eating fish.
They was imported to help control parasite problems associated with aquaculture. Black carp devastate native mollusks. Native mussels is already endangered in Iowa and at risk of going extinct where black carp is present.
An experienced person will see that black carp are not easy to identify. They possess a cylindrical body shape. Also, there’s a distinctive dark streak on their flank.
Black carp is shy compared to the other species. They also hangs out more in deeper water. Not seeing them in the catch reports isn’t because they’re not in the water.
It’s because they’re hiding. And while doing so, they’re quietly destroying the aquatic ecosystem’s foundation.
So knowing these five will help you read the water.
And it will turn a generic day of fishing into something more like a targeted search. You’ll focus your efforts on certain species. This might be important to you if you are concerned about boat safety or if you wish to preserve native mussels.
Or maybe you’re simply curious what you’ve been catching and just don’t know where to look. Next time you’re out casting a line in Iowa, pay close attention to the habitat and the scales. There may be much more there than meets the eye.