What Do Crayfish Eat? (And Why They Can Wreck Your Pond Liner)

What Do Crayfish Eat — and Why They Can Be a Problem in Your Pond

Crayfish showing up in a pond usually gets one of two reactions: mild curiosity, or genuine concern once someone realizes what these things are actually capable of doing to a pond over time. Both reactions are fair. Here's what crayfish eat, and why their diet and digging habits together make them worth paying attention to.

What Crayfish Actually Eat

Crayfish are omnivorous scavengers, and not picky about it. Their diet includes:

• Decaying plant matter and algae
• Small insects, larvae, and worms
• Snails and other small invertebrates
• Fish eggs — including eggs from fish you may have intentionally stocked
• Dead or dying fish
• Aquatic plants, including the roots of plants you may have specifically planted

In small numbers, this scavenging role isn't necessarily a problem — crayfish cleaning up decaying organic matter is a normal part of a pond ecosystem. The trouble starts when a population grows unchecked.

The Real Issue: What Crayfish Do to Pond Liners

This is the part that catches a lot of pond owners off guard. Crayfish are burrowers. They dig into soft banks and pond edges to create shelter, and in a lined pond, that digging can go straight through the liner. A single crayfish burrow might seem minor, but an established population can riddle a bank with tunnels, leading to slow leaks that are frustrating to diagnose — you notice your water level dropping and can't figure out why, and the actual cause is buried under the bank line.

If you're noticing unexplained water loss and you know crayfish are present, checking the bank for burrow holes is worth doing before you assume the problem is somewhere else.

Signs You Might Have a Crayfish Population Problem

• Small holes or tunnels along the pond's bank, especially near the waterline
• Unexplained or gradual water level drops
• Cloudy water from constant bottom disturbance
• Missing or damaged aquatic plants, particularly roots
• Noticeably fewer fish eggs surviving to hatch than expected

Managing a Crayfish Population

You don't necessarily need to eliminate crayfish entirely — a small population usually isn't worth the effort to fully remove, and they do provide some genuine scavenging benefit. But if numbers are getting out of hand:

• Trapping is the most direct way to reduce numbers without harming other pond life
• Predatory fish like larger bass or catfish will eat juvenile crayfish and can help keep a population in check naturally
• Checking and repairing your liner proactively matters more here than with most pond pests, given the burrowing risk — if you're dealing with an established population, it's worth inspecting your pond liner for damage rather than waiting for a leak to show up on its own

Frequently Asked Questions

Are crayfish bad for ponds?
Not inherently — a small population plays a normal scavenging role. The risk comes from unchecked population growth, which leads to bank burrowing (liner damage) and increased predation on fish eggs and aquatic plants.

How do I know if crayfish are causing my pond to leak?
Look for small burrow holes along the bank near the waterline. If you're losing water gradually and can't identify another cause, a liner inspection focused on the bank area is a reasonable next step.

Will crayfish eat my fish?
They're more of a threat to fish eggs and very small fry than to established adult fish, though a large aggressive crayfish can occasionally target vulnerable or injured fish.

What eats crayfish in a pond?
Larger predatory fish like bass and catfish will eat juvenile crayfish, which can help naturally limit population growth over time.

Do I need to remove all the crayfish from my pond?
Usually not. The goal is managing population size, not full elimination — a modest crayfish population isn't typically a problem on its own.

Dealing With Liner Damage or Unexplained Water Loss?

If you suspect crayfish (or anything else) has compromised your pond liner, call us at 888-825-6214 — we can help you figure out what's going on and get the right repair or replacement liner for your setup.