How to Set Up a Crayfish Tank: A Beginner’s Guide That Actually Works

So you bought a crayfish. Or you’re about to. And now you’re staring at an empty tank wondering what goes in there besides water and vibes.

Good news: crayfish are not divas. They don’t need fancy lighting, exotic substrates, or a PhD-level water chemistry routine. Bad news: most of the “12 easy steps” guides floating around the internet contradict themselves halfway through and tell you to do things that will straight-up kill your cray.

This guide is the version I wish I’d read when I started. We’ll go through every piece of gear you need, in the order you need it, and I’ll flag the stuff most beginners get wrong.

What You Actually Need (The Honest Shopping List)

Before we touch a single drop of water, here’s the list. Buy this stuff first, set it up second, add the crayfish last.

Item	Required?	Notes
20-gallon tank (minimum)	Yes	5g works for dwarf crayfish only. See sizing section below.
Sand or fine gravel substrate	Yes	Crayfish dig. Give them something to dig in.
Hides (PVC pipe, caves, driftwood (the driftwood I use for crayfish hides))	Yes	At least one per crayfish. More is better.
HOB or sponge filter (the gentle sponge filter I run in my crayfish tanks)	Yes	Bigger than the tank suggests. They make a mess.
Heater (50-100W)	Sometimes	Only if your room drops below 65°F.
Tight-fitting lid	Yes	Non-negotiable. They escape.
Water conditioner (dechlorinator (what I use every water change))	Yes	Seachem Prime or API Tap Water Conditioner.
Liquid test kit (API Master)	Yes	Strips lie. Get drops.
Air pump + airstone	Optional	Helpful, not mandatory.
Live or fake plants	Optional	They will eat or shred most live plants.
LED light	Optional	Crayfish don’t care. It’s for you.

That’s it. No special crayfish-branded gear, no $200 sumps, no UV sterilizers. Total cost for a basic-but-good setup: $80–$150 if you shop smart.

Now let’s actually build it.

Step 1: Pick the Right Tank Size

This is where I have to clear something up, because a lot of guides (including the older version of this one, sorry) give wishy-washy answers.

Standard adult crayfish (procambarus clarkii, blue crayfish, electric blue, white specter) need a 20-gallon long (the size most adult crayfish actually need) minimum. That’s the floor, not the ceiling. A 20L gives them enough footprint to dig, hide, and roam without constantly running into the glass.

Dwarf crayfish (CPO, Mexican dwarf, brazos dwarf) can live in a 5-10 gallon. They top out at 1.5–2 inches and don’t need the same real estate.

If you’re keeping more than one, add another 10 gallons per extra crayfish minimum — and even then, they’ll fight unless you have tons of hides and visual barriers. Crayfish are territorial little gladiators. Read our guide on keeping two crayfish together before you try it.

For a deeper breakdown by crayfish size and species, check this dedicated tank-size guide.

Footprint matters more than gallons. A 20-long (30″x12″x12″) beats a 20-tall (24″x12″x16″) every single time. Crayfish live on the bottom. They don’t care about vertical water column.

Step 2: Add the Substrate

Crayfish are burrowers. In the wild, they dig little tunnels in the muddy banks of streams and ditches. In your tank, they’ll do the same thing — minus the mud.

Use sand or small-grain gravel. Pool filter sand, aquarium sand (the fine sand that lets crayfish actually burrow), or fine pea gravel all work. Avoid huge gravel chunks (they can’t sift through it) and razor-sharp substrates (they can damage soft post-molt shells).

Layer it 2–3 inches deep. Deep enough to dig, shallow enough that you can actually clean it during water changes. Anything deeper than 4 inches just becomes an anaerobic gas pocket nightmare.

Rinse it before you add it. I don’t care what the bag says about being “pre-washed.” Dump it in a bucket, run a hose through it until the water comes out clear, then add it to the tank. Skip this step and your tank will look like chocolate milk for a week.

If you want specific brand recs, here’s our roundup of the best substrates for crayfish.

Step 3: Add Hides (This Is Non-Negotiable)

A crayfish without a hide is a stressed crayfish, and a stressed crayfish is a dead or aggressive crayfish.

Provide at least one hide per crayfish. More if you can. Crayfish use hides to:

• Sleep during the day (they’re crepuscular).
• Hide while molting — when they’re soft and totally defenseless.
• De-escalate fights with tank mates by retreating.

What works as a hide:

• PVC pipe (— the cheapest cave a crayfish actually uses) cut into 4–6 inch sections (the cheapest, most-used hide on earth)
• Coconut huts from any pet store
• Caves stacked from slate or river rocks
• Driftwood with hollows underneath
• Terra cotta pots flipped on their side

What doesn’t work:

• Anything with sharp edges
• Hides that can topple onto your crayfish (stack rocks carefully or glue them)
• Anything painted, plastic-coated, or “decorative” without a clear food-safe label

Step 4: Add Plants (Knowing They’ll Get Wrecked)

Here’s the truth: crayfish eat plants. Or rip them up. Or use them to climb out of the tank. Sometimes all three.

Hardy plants that survive crayfish abuse:

• Java fern attaches to driftwood and tastes terrible to crayfish.
• Anubias is rhizome-attached so they can’t uproot it.
• Java moss — they’ll graze on it but it grows back fast.
• Hornwort — floating, prolific, and even if they shred it the pieces just keep growing.

Plants they’ll destroy in a week:

• Anything with a soft stem (Cabomba, Anacharis)
• Anything in a pot with delicate roots
• Most carpet plants

Use rhizome plants attached to driftwood or rocks. Don’t bury them in substrate — your crayfish will pull them out for fun.

If you’re not sold on the live plant battle, plastic plants are honestly fine. Crayfish don’t care.

Step 5: Install the Filter

Crayfish are messy. They tear up food, leave half-eaten chunks everywhere, and produce way more waste than their size suggests.

Get a filter rated for double your tank size. A 20-gallon tank? Get a filter rated for 40 gallons. This isn’t optional — undersized filtration is the #1 reason crayfish tanks crash.

Filter options that work:

• Hang-on-back (HOB) — easy, cheap, replaceable cartridges. Aqueon QuietFlow or AquaClear are reliable.
• Sponge filter — cheap, gentle, doubles as biological filtration. Great for dwarf crayfish.
• Canister filter — overkill for one cray, perfect if you’re stocking heavy.

Avoid: undergravel filters (they get blocked by burrowing) and filters with strong intake currents (they suck up molted exoskeletons and clog).

For specific picks, here’s our filter guide for crayfish tanks.

Step 6: Heater (If You Need One)

Crayfish thrive at 65–75°F (18–24°C). Most rooms in temperate climates sit in this range naturally — meaning a lot of keepers don’t need a heater at all.

You need a heater if:

• Your room drops below 65°F overnight
• You live somewhere with cold winters and minimal heating
• You’re breeding (stable warmer temps speed up egg development)

You don’t need a heater if:

• Your room stays 68–75°F year-round
• You have dwarf species, which tolerate slightly cooler temps

If you do buy one: get an adjustable thermostat heater (the heater I trust to keep my crayfish tank stable) (not a preset one) and size it correctly — 50W for tanks under 20g, 100W for 20–40g. Always pair with a thermometer; preset heaters lie.

A heater that overshoots will cook your crayfish. Read why crayfish die — overheating is in the top three causes.

Step 7: Lighting (Whatever You Want)

Crayfish are nocturnal-ish. They don’t care about your light.

Pick a light because you want to see your crayfish, not because they need it. Standard LED aquarium lights are fine. Run them 6–8 hours a day max — longer encourages algae blooms.

If you have live plants, you’ll need a plant-grade light. Otherwise any cheap LED works.

Step 8: Fill the Tank With Water (And Treat It)

This is where most “expert” guides go off the rails by telling people not to use tap water. That’s wrong. Tap water is fine — you just need to treat it.

The process:

1. Fill the tank with regular tap water (cool to lukewarm).
2. Add a dechlorinator like Seachem Prime or API Tap Water Conditioner at the dose for your tank volume.
3. Wait 5 minutes. That’s it. The chlorine and chloramine are neutralized.

You do not need to:

• Let water “sit for 24 hours” (this only works for chlorine, not chloramine — most municipal water has chloramine now)
• Use bottled water (waste of money)
• Use distilled or RO water (actually bad — strips the minerals crayfish need for shell development)

Don’t fill the tank to the top. Leave 2–3 inches of airspace. Crayfish climb, and a tank filled to the brim is just a stepping stone to the floor. More on this in our crayfish tank water depth guide.

Step 9: Cycle the Tank Before Adding Crayfish

This is the step everyone skips and everyone regrets. Cycling means establishing the beneficial bacteria that convert toxic ammonia to nitrite, then to less-toxic nitrate.

The cycle takes 4–6 weeks. Yes, weeks. No shortcuts.

Here’s how it actually works (the version that’s correct):

1. Add a source of ammonia to the empty tank — pure ammonia drops, a piece of fish food, or a bottled bacteria starter like Seachem Stability or Fritz Zyme 7.
2. Test daily with a liquid kit. Ammonia will spike, then fall as nitrite-eating bacteria establish.
3. Nitrite will spike next, then fall as nitrate-eating bacteria establish.
4. When ammonia and nitrite both read 0 ppm and nitrate reads above 5 ppm, the cycle is complete.

The wrong version that’s everywhere online: “Add more ammonia to reduce ammonia.” No. That’s not how nitrogen chemistry works. Adding more ammonia just gives your bacteria more food to multiply — which speeds the cycle, but the levels still need to fall to zero before the tank is safe.

Want to skip the cycling wait? Get a few cups of established filter media or substrate from a healthy aquarium (a friend’s tank, your local fish store). Real seeded media cuts the cycle to 1–2 weeks.

Step 10: Set the Right Water Parameters

Here’s what your water should actually look like once you’re cycled and stocked:

Parameter	Ideal Range	Notes
Temperature	65–75°F (18–24°C)	Stable matters more than exact.
pH	7.0–8.0	Slightly alkaline. Crayfish need calcium-rich water.
GH (general hardness)	8–20 dGH	Hard water is good — calcium for shells.
KH (carbonate hardness)	4–10 dKH	Stabilizes pH.
Ammonia	0 ppm	Anything above 0 is toxic.
Nitrite	0 ppm	Same — toxic at any level.
Nitrate	<40 ppm	Not zero. Some nitrate is normal in a cycled tank.

The old version of this guide listed nitrate as 0 ppm. That’s not achievable in a cycled, stocked tank — and if your nitrate actually reads zero, your tank isn’t cycled. Aim to keep it under 40 ppm with weekly water changes.

Crayfish need calcium for their exoskeletons. If you’re in a soft-water area, drop a cuttlebone in the tank or use crushed coral in your filter to bump up GH and KH naturally.

Step 11: Acclimate and Add Your Crayfish

You finally got to the fun part. Don’t blow it by dumping the cray straight in.

Drip acclimation is best:

1. Float the bag (or transfer to a small container) in the tank for 15 minutes to match temperature.
2. Open the bag. Use airline tubing tied in a loose knot to drip tank water into the bag — about 2–4 drops per second.
3. Continue for 30–45 minutes until the bag volume has roughly tripled.
4. Net the crayfish out and place it in the tank. Don’t pour the bag water in.

Why net them out? Bag water often carries ammonia and waste. Pouring it into your freshly cycled tank is asking for an instant ammonia spike.

Drop the cray gently near a hide. They’ll vanish for a few hours, possibly a few days. That’s normal. Don’t poke at them.

Step 12: Cover the Tank (Seriously, Don’t Skip This)

Crayfish are escape artists. They will:

• Climb the heater cord
• Climb the filter intake
• Walk out on the airline tubing
• Use plants as ladders
• Pull themselves up on a slightly-too-high water level

A crayfish on the floor survives 5–7 days out of water — but you probably won’t find them in time, and if you have pets or kids it’s a disaster. Here’s why they keep trying to escape.

Use a glass canopy with all openings sealed — wire mesh over the filter slot, sponge filter inside the lid gap, every cable port covered. Mesh tape or aquarium-safe egg crate works great.

Test the lid by trying to lift the corners. If you can flex it open, your crayfish can flex it open.

Feeding (The Quick Version)

I know this guide is about setup, but you’ll need food day one.

• Sinking pellets or wafers are the staple. Hikari sinking wafers (— what I drop in for my cray), Repashy gel food, and shrimp pellets (the food my cherry shrimp actually swarm) all work.
• Supplement with: blanched veggies (zucchini, spinach, peas), occasional protein (frozen bloodworms, krill), and calcium sources (cuttlebone, eggshells).
• Feed once daily, only what they finish in 5 minutes. Remove leftovers.

For the full feeding routine, see our crayfish care guide.

Tank Mates: Should You Even Bother?

Short answer: probably not. Crayfish will eat or maim most tank mates.

Long answer: dwarf crayfish are the safest with tank mates (small tetras, fast schooling fish). Adult standard crayfish? Plan for solo, or accept casualties. If you’re considering a community tank with blue crayfish specifically, read that guide before stocking.

FAQ

Can I put a crayfish in a 5-gallon tank?

Only if it’s a dwarf species (CPO, Mexican dwarf). Standard crayfish need 20 gallons minimum. A 5-gallon for a full-size cray means stunted growth, aggression, and short lifespan.

Do crayfish need an air pump?

Not strictly. They breathe oxygen dissolved in water through gills, and a properly-sized filter creates enough surface agitation for gas exchange. An airstone helps in tanks over 30g or in warm rooms (warmer water holds less oxygen), but it’s not mandatory.

How long should I cycle a crayfish tank?

4–6 weeks for a fishless cycle from scratch. 1–2 weeks if you seed with established filter media from another tank. Test until ammonia and nitrite both read 0 ppm and nitrate is detectable.

Do crayfish need a heater?

Only if your room temperature drops below 65°F. They thrive in 65–75°F, which most heated indoor rooms hit naturally. If you keep them, get an adjustable thermostat heater, not a preset one.

Can crayfish live with bettas?

Usually no. The crayfish will catch the betta when it sleeps near the substrate. Even if the betta is fast, one slip and it’s lunch. Dwarf crayfish + bettas can sometimes coexist in heavily planted tanks, but it’s a gamble.

What’s the easiest crayfish for beginners?

Electric blue crayfish (Procambarus alleni) and Mexican dwarf crayfish (CPO). Hardy, colorful, widely available, and tolerant of beginner mistakes.

Final Thoughts

Setting up a crayfish tank isn’t complicated — it’s just unforgiving. Skip the lid and they escape. Skip the cycle and they die. Use untreated tap water and they die faster. Get the basics right and you’ll have a weird, smart, surprisingly interactive pet that’ll outlive most other freshwater inverts.

Build the tank, cycle it, then bring the crayfish home. Not the other way around. That’s the whole secret.