Terracotta pots and ceramic containers make excellent aquarium accessories for fish, and they're one of the most practical hiding spots you can add to a tank. Plain unglazed terracotta pots are aquarium-safe, pH-neutral, and highly effective as shelter for bottom-dwelling fish, breeding fish, and any species that naturally retreats to caves or crevices. A $2 clay pot from the garden section does the same job as a $15 commercial aquarium cave.
The term "fish pot accessories" covers both the pots themselves and the modifications that make them more functional: grinding down rough edges, drilling holes, adding substrate or planting on top, and combining multiple pots into structures. Here's a complete guide to using pots in your aquarium safely, which fish benefit most, and what other accessories pair well with pot-based setups.
Are Terracotta Pots Safe for Aquariums?
Plain unglazed terracotta pots are safe. They're made from fired clay, which is chemically inert and won't leach harmful substances into the water. You can buy them from any garden center or hardware store and drop them in after a good rinse.
The exceptions are:
- Glazed pots: Many decorative glazes contain heavy metals (lead, cadmium) or other compounds that aren't aquarium-safe. Avoid any pot with a shiny glaze unless it's specifically labeled aquarium-safe.
- Painted pots: Decorative paint that isn't aquarium-safe will peel and leach. Acrylic paints marketed as aquarium-safe can be used, but undecorated terracotta is the safer default.
- Pots with drainage holes pre-drilled: These are fine. The hole is a feature, not a problem. Many fishkeepers prefer pots with a drainage hole as a secondary entrance.
Before adding any terracotta pot to a tank, scrub it with a clean brush under dechlorinated water. Don't use soap. Rinse thoroughly, then let it sit in a bucket of dechlorinated water for 24 hours to leach out any residual mineral deposits.
Which Fish Benefit Most from Pot Hides
Plecos and Loricariidae
Plecos strongly prefer enclosed hiding spaces. They're nocturnal and spend most daylight hours wedged into dark crevices. A terracotta tube or cave is genuinely necessary for most pleco species, not just a nice-to-have. A common pleco (Hypostomus plecostomus) in a tank without hiding spots shows visible stress, paling out and staying flat against the glass rather than exploring.
For smaller pleco species like bristlenose (Ancistrus sp.) and rubber lip plecos, a 4-inch diameter terracotta tube or pot on its side is ideal. For large plecos (royal plecos, sailfin plecos), you need correspondingly larger containers: a 6-8 inch pot or a PVC pipe section.
Cichlids
Many cichlid species are cave spawners and will breed in terracotta pots. Ram cichlids (Mikrogeophagus ramirezi), German blue rams, and apistogrammas regularly use 2-3 inch pots or overturned pots with a chipped entrance as spawning sites. Convict cichlids will use almost any enclosed space.
For community tanks with cichlids, multiple pots reduce aggression by giving each fish or pair a territory to claim and defend. Three pots in a 40-gallon tank with four cichlids maintains visible hierarchy without constant chasing.
Shrimp
Cherry shrimp, Amano shrimp, and other dwarf shrimp use terracotta pots for molting cover. When a shrimp molts, it's temporarily vulnerable and will retreat to the smallest enclosed space available. A small 1-2 inch pot with a hole just large enough for the shrimp to enter protects it during the 24-48 hours it takes for the new shell to harden.
Shy and Timid Species
Khuli loaches, otocinclus catfish, cory catfish, and many gobies appreciate enclosed hiding spots. Even fish that don't strictly need caves do better with them available. Research consistently shows that fish with access to cover display less stress behavior and stronger coloration.
How to Prepare and Modify Pots for Aquarium Use
Smoothing Rough Edges
New terracotta pots sometimes have sharp edges around the rim or at the drainage hole that can injure fish. Run a coarse sandpaper block or a diamond file around any sharp edges before adding the pot to the tank. Test with your fingertip first: if it snags your skin, it can injure a fish.
Creating Entrance Holes
If you want a cave with a specific entrance size, use a Dremel rotary tool with a diamond-cut bit to grind an opening in the side of the pot. Clamp the pot, wear eye protection, and work slowly to avoid cracking the clay.
A good guideline for entrance hole sizing: - Bristlenose pleco: 2-inch diameter opening - Common pleco: 3-4 inch opening - Ram cichlid or apistogramma: 1.5-2 inch opening - Kuhli loach: 1-inch opening (they wedge into very tight spaces)
After drilling or grinding, rinse the pot thoroughly to remove clay dust, then soak for 24 hours before adding to the tank.
Stacking and Building Structures
Multiple pots can be stacked or arranged to create cave complexes. Three 4-inch pots arranged in a triangular stack create a structure with multiple entrances and levels. Use aquarium-safe silicone adhesive (the same silicone used for tank sealing) to bond pots if you want a stable structure.
Unsiliconed stacked pots will shift when fish move through them. That's fine for large fish, but for small fish or shrimp tanks, siliconing stacked pots into a fixed structure is safer.
Planting on and Around Pots
Java moss, java fern, and anubias all attach to the exterior of terracotta pots naturally. The slightly rough surface grips plant rhizomes well. Tie java moss around a pot with cotton thread; the thread degrades in 4-6 weeks by which time the moss has attached.
Anubias and java fern attach to any rough surface with their rhizomes. Use a rubber band or cotton thread to hold them against the pot surface for 2-4 weeks. Once attached, they grow from the pot surface and eventually cover it completely.
This technique creates a moss cave or plant-covered hide that looks far more natural than bare terracotta and provides additional cover for fry and small invertebrates.
Other Accessories That Pair Well with Pot Setups
See our Best Freshwater Aquarium Accessories guide for complete recommendations on cave-compatible accessories.
Substrate
Fine sand substrate works better with pots than coarse gravel. Corydoras and loaches sift through the sand near pot entrances. Coarse gravel makes it harder for bottom dwellers to position themselves comfortably against the pot entrance.
CaribSea Super Naturals Sunset Gold Sand and Carib-Sea Peace River Gravel both work well. Fine sand in the range of 0.5-2mm is the general recommendation for bottom-dwelling tank inhabitants.
Live Plants
Java fern attached to the pot surface, with additional hornwort or water sprite as floating cover, creates a naturalistic cave setup. The floating plants diffuse lighting and reduce stress for light-sensitive species.
Commercial Cave Accessories
If you prefer a ready-made option, Aqua Natural's Sugar White Cave Ornaments and Penn-Plax Shale Step Ledge aquarium decoration replicate the look and function of natural caves. These are typically ceramic or resin, priced at $8-25, and come in various sizes. Check our Buy Aquarium Accessories Online guide for current options.
FAQ
Can I use regular garden pots without any modification? Plain unglazed terracotta garden pots work directly with only a rinse and soak. Avoid any pot with paint, metallic finish, or ceramic glaze. The drainage hole is fine as-is and often functions as a useful secondary entrance for fish.
Will terracotta pots change my water chemistry? Unglazed terracotta has minimal effect on water chemistry. Some fishkeepers report a very slight pH increase in soft-water tanks, but the effect is small and temporary as the pot's surface gradually builds up a biofilm layer. If you're keeping very pH-sensitive species like wild-caught cardinal tetras (pH 4.5-5.5), monitor pH after adding the pot for the first week.
How do I clean pots once they're in the tank? Rinse with old tank water during water changes. A stiff brush removes algae and debris from the exterior. If the pot is being used as a breeding cave, don't disturb it during active spawning. After a breeding cycle ends, remove the pot, scrub with a brush under dechlorinated water, and reinstall.
My pleco won't use the terracotta cave I added. Why? Plecos are creatures of habit. If the pleco already has a established hiding spot (a corner, under a rock, behind the filter), it won't immediately switch to the new cave. Position the pot in a similar location to the current hiding spot, ideally in a low-traffic area of the tank with reduced light. Most plecos adopt a new cave within 1-2 weeks if it's positioned correctly.
Final Thoughts
Terracotta pots are one of the most cost-effective aquarium accessories available. They work for plecos, cichlids, loaches, shrimp, and any cave-preferring species. The key details: use only unglazed pots, smooth any sharp edges, and size the entrance hole to your specific fish. Adding java moss or anubias to the exterior integrates them naturally into a planted or naturalistic aquascape. A $2 clay pot from the hardware store does everything a $15 aquarium cave does, and it lasts indefinitely.