If you ever move a fish, you’ll likely use a bucket or a bag, but there’s a science behind fish bagging if it’s going to work properly. Nathan Hill tackles something most everyday hobbyists do only a couple of times in their life and often get very wrong.
Bagging a fish properly is a skill that takes a little practice, but makes a big difference to both your fish when they need to be transported and the kudos you get from whoever receives them. It’s rather like learning to ride a bike, being something once mastered you never forget.
If you're unsure whether you should bag your fish or use a larger vessel, in more chance than not, fish will have a higher chance of survival in a plastic bag if there is a large volume of water in the bag, and enough space for oxygen.
If you need to travel some distance, it could make the big difference between fretting and checking your livestock every five seconds or enjoying a stress-free journey. Essentially, all you need is a plastic bag, an elastic band, and something to put the fish in to keep it dark and/or warm for travelling. However, there are some things to be aware of in order to avoid tragedy. Here's our guide...
Common Questions for Bagging Live Fish
Can I use any bag when bagging fish?
Ideally you want a purpose made fish bag, which will be made of clear, strong polythene. Avoid using short sandwich bags, freezer bags, or other small domestic bags, and under no circumstances use a scented bag—it’ll be toxic to fish.
Your local retailer will have bags for sale (if you ask nicely) or you can buy packs from the likes of Amazon. Aim for something around 6x20” (currently about £7.50 for 25 on Amazon.co.uk) for fish up to 2-3” long. Shorter bags are available but you’ll be grateful for the height later…
How do I tie a bag with fish in?
Watch what they do with bags in stores and copy them. Usually, they’ll roll the top of the bag down to create a floating ‘ring’, dunk the bag in the tank to fill it, and leave it floating about with its conveniently accessible opening. Don’t be tempted to get a friend to hold a half-filled bag open beside you while you try to tip fish in from a net. You may miss altogether, and often the fish jump straight back out.
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Are corners to be avoided with a fish bag?
Depending which fish you’re catching, you might want a bag with rounded edges. They’re harder to source, but if you can’t get any then you can improvise by getting some Sellotape and going over each pointed corner of the bag. This will be especially useful if you’re transporting the likes of Corydoras or Synodontis that tend to panic, dive into a corner and lock their fins. Don’t have Sellotape? Just turn the bag upside down once you’ve tied it off.
How many bags should I use when bagging fish?
It is generally recommended that you double bag all fish. If you’re moving a fish with spines (including large angelfish) or sharp teeth, take a Russian doll approach to bagging and use sometimes three bags sleeved inside each other. A lot of species have sharper edges than you might think and it's always better to be safe than sorry.
How much water to put in a fish bag?
Aim to have a one-to three ratio: one part water, three parts air. This is essential if the fish are to be bagged for a while, as it’s the air that contains the essential oxygen, and a water foiled bag will become rapidly anoxic. While it’s tempting to add lots of water, it really isn’t necessary—recent research found that the optimal amount of water for a single male Siamese fighter is just 80ml.
Should you tie a knot or band a fish bag?
It’s really hard to tie a knot in a bag with wet hands (especially if you’re inexperienced at it). Get in some thick elastic bands ahead of time and use these. Make a few twists in the top of the bag so that it’s nice and rigid, then wrap a band round and round before folding the top of the twisted bag over and hooking the band over that. A firm bag will earn you respect from whoever receives it (honestly).
Can I put multiple fish together in a bag?
Be wary of mixing fish together in a bag. Some of them (and this is especially noted with some Corydoras catfish) seem to have the ability to release a toxin that poisons themselves and their travel companions. Stick to one species per bag to be safe.
How or where should I store my live fish bags?
Now you have your fish secured and bagged, the worst thing you can do is swing them about in the light. Place the fish bags into a dark container, or wrap them in a towel or some newspapers. Being in the dark will help to calm them for their journey, and wrapping the bag in something will help to insulate it and keep them warm.
Top tip
Before you add water, fill the bag up, twist the top a few times to seal it and give it a firm squeeze. If it breaks along the seam at the slightest application of pressure, you have a duff batch. You’ll want to know this now before you fill the bag with water and fish and try to tie it (believe me, it happens all too regularly).
Tutorial: How to bag live fish
1. Roll down the bag, filling around a quarter of it with aquarium water and float it on the surface of the tank. This will keep it floating and open as you net your fish.
Make sure the bag is big enough for the fish you’re catching and be aware that some spiny travellers may need to be double bagged if their fins penetrate the first one.
2. Unroll the bag gently, remembering you have your fish inside. Once fully open, hold it so that it is hollow like a windsock. It may help to gently blow across the top of the bag to keep it inflated.
It would be a good time to assess that you have enough water in the bag — and if not add a little more.
3. Quickly snatch or pinch across the top of the bag to trap around four or five parts of air to the volume of water that you already have.
Once you’ve achieved that, gently give the bag a couple of slow twists, or twist the neck so you have a few inches of twisted bag at the top and that the bag itself is rigid and inflated.
4. Wrap an elastic band around the bottom of the twisted neck, so that it passes through itself. Pull this tight and, holding the bag high, wrap the band around the neck, with a finger or two in the end of the band being wrapped.
Keep going until you have a short length of elastic band left, with a loop in the end of it.
5. Fold the neck of the bag over on itself and hook the loop from the end of the band over it about halfway down. This will simultaneously secure the loop and top of the bag in place.
You may wish to turn the bag upside down or tape the corners curved before putting the bag into a dark wrapper to keep the fish calm.
6. Having reached the other end of your fish’s journey and, once it has been acclimatised to a new temperature, the bag can be opened very quickly by simply pulling at the loose end of the neck.
This will ping the loop of elastic from the top — at which point the band will unravel itself and be easily removed.
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