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hollow

The Hidden Hollow

The Hidden Hollow

4.8 · Based on 2,000 verified Etsy reviews

LOW STOCK - Handmade to order. Limited production capacity.
Couleur: Black
Variation

30 Day money back guarantee

Free global shipping over 30€

WhatsApp +356 9997 2230 for quick answers to your questions

5-8 Day shipping to EU, UK and USA

Buy 2+ caves, get 10% off at checkout
Regular price €36,90 EUR
Regular price Sale price €36,90 EUR
Sale Sold out
Tax included. Shipping calculated at checkout.
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Material: Aquarium safe PLA, it does not affect water parameters

 

Dimensions:

250 x 130 x 75 mm / 9.84 × 5.12 × 2.95 in
Opening: 90 x 65 mm / 3.54 × 2.56 in

Tank size in the pictures: 25x25x13 / 36x22x26

View full details

Easy to set up and style

Just place it against the glass, add substrate around it, and place plants over and inside it. That’s it. In just a few simple steps, it creates a mesmerizing mini underground world that adds depth, shelter, and a natural look to your setup.

Easy to clean

Features a large entrance that makes it easy to remove debris or waste. As an aquascaper myself, I design every cave with maintenance in mind, so it stays practical in real long term planted tank use.

Functional and Aquarium safe shelter

It creates natural hiding spots, offers shelter from bright lighting, helps reduce stress for fish and shrimp. Aquarium-Safe Material: Crafted from biodegradable, biosourced, and recyclable PLA, it does not affect water chemistry.

Customer reviews

Trusted by 12,000 customers and backed by 2,000 reviews on Etsy

why hollow?

Not all aquarium caves are created equal

Mass-produced and generic cave decor is designed to look good in photos. We create caves for real life use.
Hollow Generic caves Mass produced
Easy to clean & maintain
Tested in planted tanks
Aquarium-safe materials
Blends naturally into the tank
Designed by an aquascaper

🏡You’ve got a home. Why not your little companion too?

Comfort and security: a safe place to hide, rest, and feel protected

More natural behavior: encourages instinctive shelter-seeking and exploration

Less stress: ideal for shy, territorial, or easily stressed species

More confidence: animals that feel safe often become calmer and more comfortable in their environment

Better tank dynamics: helps create small territories and reduce aggression

Helpful in community setups: gives weaker or shyer animals a place to retreat

Extra surface for beneficial bacteria: supports biological filtration and water quality

Breeding support for some species: especially helpful for cichlids, plecos, gobies, and similar cave-using species

Suitable for 🐠🦎

The caves are suitable for all freshwater, marine and terrestrial species!

Please check the dimensions tab below "Add to cart" for precise measurements. If your animal can comfortably get through the entrance, you are good to go!

A few popular use cases:

🐠Bettas, Guppies, Tetras, Danios, Corydoras, Shrimp, Otocinclus, Kuhli Loaches, Plecos, and many more, including marine species.

🦎Leopard Geckos, Crested Geckos, Frogs, Corn Snakes, Tarantulas, Bearded Dragons, Ball Pythons and more.

📏 Will this cave fit my tank?

📏 Tank Sizes: The larger the cave is relative to the aquarium, the stronger its visual impact will be.

Please note: This listing is for the cave only, not the full aquarium shown in the photos. If you are unsure whether your animal will fit, or whether the cave will fit your tank, please refer to the Dimensions table above, below "Add to cart"

GOT QUESTIONS?

Frequently Asked Questions

About the caves

No. Every piece is made from aquarium-safe PLA that is biodegradable, biosourced, and fully inert. It will not affect your pH, hardness, or any other water parameter. Safe for fish, shrimp and marine aquariums.
Yes. Our pieces are suitable for terrariums and reptile setups as well as aquariums. Check the individual product page for compatibility details, especially dimensions, if your animal fits through the entrance comfortably, you are good to go! The rest is design preference. Disclaimer: Do not put it directly near high heat (45°C+/113°F+)
The large openings are intentional, so most caves are easy to clean with a standard aquascaping tool kit. A magnetic cleaner and a soft brush or toothbrush are highly recommended for the surrounding glass. We use the Chihiros Mini on all of our cave tanks. A regular hose is used to clean debris inside the cave.
The first step is to check the dimensions on the individual product page, below "Add to cart". If your animal can comfortably fit through the entrance, you are good to go. Beyond that, the choice is mostly visual: most caves can work in most tanks. A smaller cave works well as a subtle detail or accent piece, while a larger one creates a stronger focal point in the scape. Do not overthink it, our caves are designed to blend naturally into the setup, regardless of the style of your tank. That is exactly what they are made to do.

Shipping and ordering

Processing times: 1 - 4 days (every item is made to order and hand finished). Delivery times by destination: EU, UK and USA: 5 - 8 days. Canada: 7 - 10 days. Asia: 12 - 30 days. Australia and New Zealand: 12 - 20 days.
They are designed and made in house. Built to be sturdy and durable, they are made to hold up well during normal use and transit. Packed with care and shipped globally with tracking.
We offer a 30-day money back guarantee. If you are not happy with your order for any reason, contact us and we will sort it out. No complicated process, no awkward questions.
Absolutely. Use the live chat, WhatsApp (+356 9997 2230) or the contact page and we will get back to you quickly. We are happy to help you choose the right size or colour for your specific tank and animal.
Orders placed in the USA are shipped from our partner based in Kansas. Orders placed anywhere else in the world are shipped from Malta, Europe. Products are exactly the same in both places.

About Hollow

Hollow is a small independent business run by an aquascaper. Every design is created and tested in real planted tank conditions before it goes on sale. This is not mass-produced or dropshipping.
We started on Etsy and built our reputation there — that is where our 2,000 reviews come from. This website gives us more flexibility and lets us serve customers directly. You get the same quality on Etsy and on our website, however delivery is quicker if you order here.
Yes! Contact us on WhatsApp +356 9997 2230, tell us what animal and tank size you have. We will get back to you with a recommendation and price.
👍 just as described and fast
Jana