Cat-proof aquarium setup tips for cat owners

So you've got a cat and you're adding an aquarium — that's a completely manageable combination, but the feline factor does shape a few of your equipment choices. Before we get to cat-proofing though, the single most important thing to know before buying anything is the nitrogen cycle: a new tank needs to establish beneficial bacteria before it can safely house fish, and skipping that process is the number one reason fish die in new setups. It takes two to four weeks and costs nothing — you just need to know it's coming. Now, are you starting completely from scratch, what size tank are you thinking, and do you have a particular type of fish in mind?

Good choices on the fish — tetras and corydoras are a great peaceful community. Your cat concerns are real but very solvable. The two risks are exactly what you named: a cat that paws or sits on a flimsy lid, and a filter that sounds like a dripping tap and drives her wild. On the lid front, the solution is a proper glass canopy rather than a lightweight plastic cover — glass is heavy enough that a cat sitting on it won't bow or dislodge it, and there's no flex for a paw to get underneath. Can I ask — do you already have a tank in mind, or are you open to choosing the whole setup around what works best?

All-in-one kits are fine as a starting point, but most come with thin plastic lids that a determined cat will move. The filter situation in kits is also hit and miss for noise — many use internal filters that create surface ripple sounds your cat will fixate on. The upgrade that solves both problems in one go is switching to an external canister filter, which runs nearly silently and keeps all the gurgling outside the tank. For your 60 litre with tetras and corydoras, I'd recommend the Fluval 107 external canister filter. It's whisper-quiet, well-suited to that tank size, has excellent mechanical and biological filtration, and because all the water movement happens below the cabinet, there's no splashing sound at the surface to attract your cat's attention. Pair it with a custom-cut glass lid and you've removed both problems entirely.

Most local glaziers will cut a piece of 4mm float glass to your tank dimensions for around £15–£20 — just measure the interior rim carefully and ask them to polish the edges. Some aquatic shops also stock cut-to-size glass lids. The Fluval 107 setup is straightforward: you prime it with a hand pump, the instructions are clear, and there are plenty of walkthrough videos online. The one thing to do first is run the outlet pipe below the waterline rather than splashing on the surface — that kills any remaining surface noise and removes the last audio trigger for your cat. Once it's dialled in, the tank will be genuinely quiet.

Absolutely — the filter is what does the cycling, but it still needs time to build up the beneficial bacteria colony. Run the Fluval with a source of ammonia for three to four weeks before any fish go in. The easiest method is a few drops of pure ammonia daily, or you can use a product like Tetra SafeStart to speed things up a little. Test your water with a basic ammonia and nitrite test kit — when both read zero and nitrate has appeared, you're cycled and ready. Your tetras and corydoras will thank you for the patience.