Bottom Feeders – What Fish Are Bottom Feeders (And which to Avoid)

Kristian Ole



Human beings have a love-hate relationship with bottom feeders. On the one hand, some of the tastiest aquatic animals, like lobster, shrimp, clams, haddock, and catfish, are bottom feeders.

On the other hand, for at least the last 50 years, government agencies have warned everyone about eating bottom feeders because of contaminants they may have picked up while lurking at the bottom of lakes, rivers, ponds, bays, and the ocean. 

Who is right? Is it possible that both could be? Is it true that bottom feeder fish can be contaminated and should only be eaten sparingly, if at all? Or is it possible that while some bottom feeders will undoubtedly be contaminated by pollution, many are not, and many are quite tasty?

Here are the answers to both questions.

What Are Bottom Feeders?

catfish bottom feeder

Bottom feeders are fish (or other aquatic creatures) that spend a significant portion of its life feeding at the zone that’s at the bottom of the body of water where they live. Typically, these fish are scavengers, but not always. Many, like several freshwater catfish, are a mix of both. Bottom feeders live worldwide, in saltwater and freshwater. Some of the most popular seafood are bottom feeders.

These include, but are not limited to:

  • Lobster
  • Crabs
  • Shrimp
  • Clams
  • Flounder
  • Haddock
  • Catfish
  • Halibut
  • Bass
  • Oysters

In addition, many bottom feeders are not that popular or even regularly consumed by humans. Those include, but are not limited to:

  • Plaice
  • Sole
  • Eel
  • Grouper
  • Carp
  • Snapper
  • Sardines
  • Shark

Chances are, whether you knew it or not, you have been a regular consumer of bottom feeders your entire life. You probably have eaten bottom feeders that might have elevated levels of chemicals like mercury and did not know it.

Related article: What do the largemouth bass eat?

Are Bottom Feeders Safe To Eat?

If you have ever had fish chowder, you most certainly have eaten bottom feeders. Additionally, some bottom feeders are so delicious that you would eat them even if they were dangerous.

Fortunately, you do not have to choose between that lobster or oyster dinner and brain damage from mercury poisoning. Sure, there are some fish that you probably should only eat occasionally, if at all. That holds for some mid-level and topwater fish as well, though. It depends on what the fish has been exposed to, how long it has been exposed and whether it is contaminated.

They Are What They Eat

Conventional wisdom says that if you eat enough vegetables, protein, and fruits, lay off the sugar, and drink a lot of water, chances are you will be healthy. Conversely, if you enjoy cake for breakfast, pie for lunch, and ice cream for dinner, washed down with sugary soft drinks, that will reflect poorly on your health.

The same principle holds for bottom feeders, but probably not exactly as you envisioned.

Several aquatic bottom feeders will eat whatever dead thing they can find while wallowing in the mud. Those bottom feeders will usually pick up whatever chemicals have leached into the bottom of the body of water in question. The chemicals they can pick up are lead, mercury, radioactive waste, petroleum products, etc.

Other bottom feeders, though, do not run the same risk because they generally will only eat fresh dead things and fall to where the bottom feeder found them. A few, like flounder or some catfish, will actively hunt prey, even though they prefer hanging out at the bottom and scavenging in a pinch.

The moral of that story is that you need to research all aquatic levels of feeders. Not all bottom feeders are bad for you. Not all bottom feeders are good for you.

flounder bottom feeder

Which Fish Are Bottom Feeders and Which Fish Are Not 

The following is a rundown of a few very popular fish and whether they are bottom feeders or not.

Is Flounder a Bottom Feeder?

Yes. While adult flounders will often hunt prey or ambush larger prey, juvenile flounders will eat crustaceans and the slow spawn of other fish. Adult flounders will also sometimes eat shrimp, smaller fish, and crustaceans. 

Is Tilapia a Bottom Feeder? 

Tilapia technically are not bottom feeders, but they are opportunistic feeders. They eat algae and lake plants, so they will stay near the top of the water column when food is plentiful. When it is not, they will head to deeper water in search of food, eventually going all the way down if necessary. 

Is Cod a Bottom Feeder? 

Cod are bottom feeders and will spend most of their life at or close to the bottom of a body of water. They eat shrimp, invertebrates, small fish, sand eels, and herring. Cod do not live exclusively on the bottom, but they often will suspend near the bottom of a body of water.  

Related article: What size crappie should you keep for eating?

Other Bottom Feeders

There are many other bottom feeders out there, not the least being shellfish. In addition, many bottom feeders also eat catfish and haddock, halibut, and both large and smallmouth bass.

Fish That Are Not Bottom Feeders 

With so many popular bottom feeders, you might be wondering which fish are not bottom feeders? There are many. The most famous is probably trout or tuna. Pacific sardines are not considered bottom feeders, and neither are most salmon. Finally, Atlantic mackerel is not a bottom feeder and is an omega-3 fatty acid powerhouse. 

Bottom Feeder Fish Not To Eat

atlantic cod bottom feeder

The list of bottom-feeder fish not to eat is lengthy, but really, only a few should be off-limits because of health reasons. Staying away from fish like Atlantic cod is important because the fishery off the east coast has struggled for over 50 years, and while it is recovering, it has a ways to go.

You should keep in mind that it is ok to eat almost all types of fish once in a while with most fish. There are very few fish that you should avoid at all costs unless you are pregnant.

The following is a partial list of fish you should not eat or only eat sparingly.

  • Eel: High rates of PCBs and mercury, particularly off the East Coast.
  • Bluefish: High rates of PCBs, mercury, and petroleum
  • Striped Bass: High rates of PCBs
  • Imported catfish: These tend to be high in antibiotics and heavy metals
  • Imported shrimp: These tend to be high in antibiotics and heavy metals


Bottom feeders are a sizable population and come in all shapes and sizes. Not all bottom fish are unhealthy, and many are good for you. However, understanding the fish that you should not eat is key to avoiding some of the dangers some bottom fish pose.


About Kristian Ole

Kristian Ole Rørbye, a marine biologist and seasoned angler, shares his fishing adventures and expertise on FishingKris. Join him as he explores the world's waters, one cast at a time.

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