Fancy goldfish in a bowl? Here's why that harms them

Congratulations on the new goldfish — but I want to flag something important before you get them settled in. A bowl is genuinely harmful for fancy goldfish, and I don't say that to make you feel bad — it's just that bowls are still sold and marketed as if they're fine, and they really aren't. Fancy goldfish are big waste producers, and without filtration, ammonia builds up quickly and starts poisoning them within days. Bowls also have too little surface area for oxygen exchange, and fancy varieties — orandas, ranchus, ryukins — are already prone to swim bladder issues that get worse when they're cramped. Which variety did you get, and do you have the bowl at home already or are you still at the planning stage?

That happens a lot, unfortunately — pet shops don't always join the dots for you. The good news is you've caught this before the fish are in it. Two orandas is a lovely choice, but they need at least 100 litres between them as adults, and they grow faster than people expect. More immediately, they need a proper filter running before they go in — that's the nitrogen cycle I'd normally talk you through first. Cycling a tank lets beneficial bacteria establish so ammonia and nitrite don't spike and kill the fish. How quickly are you able to get a proper tank sorted? That'll help me work out the safest plan for tomorrow's delivery.

For two orandas the Fluval Flex 57 Litre is the tank I'd point you to as a starting point — it's not forever-sized but it'll do for juvenile orandas while you plan a larger upgrade, it has a genuinely good built-in filter for the volume, curved glass, and it comes as a complete kit including lighting. It's widely available on Amazon UK and usually arrives next day. Critically, you'll also want to pick up a bottle of Tetra SafeStart or Seachem Stability — these contain live bacteria that let you cycle the tank much faster, which matters when your fish are arriving tomorrow. Add the bacteria, let the filter run for a few hours, then add the fish slowly and do daily water tests for the first two weeks. It's not instant, but it's infinitely safer than the bowl.

You're right to push back on that — honestly, if budget and space allow, go straight for the Fluval Flex 123 Litre instead. It's the bigger sibling of the same tank, same design and filtration quality, and it means you won't need to upgrade again in 18 months when the orandas have grown. Orandas can reach 20–25cm including their wen, so they outgrow smaller tanks faster than people expect. The 123L gives you proper swimming space, more stable water chemistry because larger volumes dilute waste better, and it's still a clean, manageable tank for a home. Either way, ditch the bowl — even as a temporary measure it'll cause stress and ammonia poisoning before the week is out.

Yes — a few things that genuinely matter. A water conditioner like Seachem Prime to dechlorinate tap water before it touches the fish. A liquid test kit, not strips — the API Freshwater Master Test Kit is the one to get, it tests ammonia, nitrite, nitrate and pH and you'll be using it daily at first. A bottle of Seachem Stability or Tetra SafeStart for the fast-cycle bacteria. And a thermometer — goldfish do best between 18–22°C so you don't need a heater, but you do need to know what temperature you're working with. That's genuinely it. Set the tank up tonight, add conditioned water, dose the bacteria, run the filter, and your orandas will have a far better start than a bowl would ever give them.