Skip to main content

Emergency Supplies to Keep for Freshwater Fish

Marie is a lover of everything about and inside of aquariums. Among other friendly creatures, she has a turtle that she adores.

The following supplies are attainable items that should be kept in the household. Aquarists do not have to have these items, but they are good to have on hand in case the unexpected happens.

It is better to have these items bought and available than to have to go out and buy them during the time of emergency, because a) time is essential, and you may not have the time or the transportation to get the needed items; b) the store may be sold out and you would waste more time hunting for said items; c) it gives you peace of mind to already have them on hand.

This article covers the following supplies for freshwater fish and the emergencies they can help with:

  • Freshwater Aquarium Salt (Injuries and Illness)
  • Peas (Constipation)
  • Active Carbon (Poisoning)
  • Backup Accessories (Malfunctions)
  • Zeolite (Uncycled Water)
  • Battery-Operated Air Pump (Power Outages)

Freshwater Aquarium Salt

For Injuries and Illnesses: Every fish keeper knows that at some point a fish will get ill, or at least hurt. You could buy some medicine in advance as a safety precaution, but fish medications often causes more harm than good. You’d have to be absolutely certain what the problem is, and you need to know if it can harm other species in the same tank. All meds have different effects.

Aquarium salt covers a range of illnesses:

  • It removes external parasites such as ich.
  • It prevents bacterial infections on fish with torn fins or open sores.
  • It treats external fungi.
  • It can even protect fish from nitrite poisoning during a cycling tank.

Because of this range, it’s the best treatment to keep on hand, especially when you don’t know what you are dealing with. If specific medication is still required, freshwater salt will often help the situation until you have time to go to the store.

Disadvantages to Salt

The drawback to using salt is that it can harm invertebrates and scaleless fish (like cats), so it is best to either use no more than a tablespoon of salt for every five gallons, or treat fish separately. Remember that salt doesn’t go away through evaporation; it stays in the water. The only way to remove salt from a tank will be through a couple of large water changes once it has dissolved. It is also best to put salt in a container of aquarium water and pour this water into the tank, for adding salt directly into the tank can burn fish gills.

FYI: If your fish has torn fins or open sores, you’ll want to do a 30% water change to also prevent bacterial infection, unless you had performed a water change very recently.


For Constipation: That’s right; whether frozen or raw, always have some peas in your fridge in case of overfeeding. If poor water quality isn’t the number one cause of aquarium fish deaths among new hobbyists, then it has to be overfeeding.

Fish in the wild don’t normally have enough food at a time to gorge themselves. They eat tiny, tiny bits of food here and there, so their stomachs weren’t designed to eat big meals like you and me. And because they are always in search for food in the wild, they will always eat whether or not they have had their fill. A lot of people won’t realize they are giving too much to their fish until it is too late.

Identifying an Overfed Fish

When fish are overfed, their stomachs will bulge and their scales will start to stick out because of their expanding bellies. They’ll also swim with an imbalance and hang around the top of the tank, unable to stay down at the bottom. This illness is fatal. Obviously the person needs to stop feeding the fish, and not feed it for a few days to a week once this happens, but by then it could be too late.

Scroll to Continue

Read More From Pethelpful

How to Give Peas to Fish

Cooked insides of a pea are the equivalent to our laxatives. It will flush out remaining food in the stomach, so if you had just fed the fish and learned what’s wrong with it, here’s what to do:

  1. Take a cold or frozen pea and put it in hot water.
  2. Once it is warm, peel off the skin, because fish have a hard time digesting the skin (the opposite of what you want to happen).
  3. Take some of the soft pea gut (makes sure isn’t hot!) and feed it to the fish. This will discard any amount of food that was recently eaten by it.

Keep peas in the freezer so it keeps, and it will always be there just in case.


Active Carbon

For Poisoning: Active carbon is often used as filter media, but most advanced aquarists don’t bother with the stuff, arguing that it isn’t necessary. Active carbon is supposed to keep the water clear and free of smells, but many will claim those conditions should be caused by frequent water changes and overall good fish keeping, not because of carbon. It certainly doesn’t hurt animals by using carbon as regular filter media, but if you don’t need or use it for filtration, keep some on hand anyway. You’ll never know when you’ll need it.

Active carbon can remove (often absorb) certain toxins in your tank, making it safe for fish. So if something toxic gets into your tank, there’s a chance charcoal can filter it out. It depends on what it is, though.

What active carbon can remove:

  • medications
  • chlorine
  • chloramines
  • hydrogen peroxide
  • bleach
  • tin
  • pesticides
  • insecticides
  • gold
  • acetic acid
  • vinegar
  • soap
  • iodine
  • silver
  • mercury
  • detergents

To a much lesser extent, it can also remove the following:

  • iron
  • lead
  • nickel
  • titanium

Depending on the amount, there’s no guarantee active carbon will get rid of all these contaminants, just some of it, which is why it is important to perform several water changes in addition to adding/replacing active carbon when the water has been contaminated by one of these toxins.

What active carbon does not remove:

  • ammonia
  • nitrites
  • nitrates
  • microbes
  • sodium
  • cadmium
  • fluoride
  • hardness
  • zinc
  • copper
  • carbon dioxide

Backup Accessories

For Malfunctions: Okay, so this is a bundle of items. Have a backup of every essential device in your current aquarium. This includes:

  • a filter
  • a heater (for tropical fish)
  • a thermometer
  • a tank, or at least a substitute tank like a large bucket or tub

You’ll never know when you need to set up a new tank because of a parasitic outbreak, fish aren’t getting along with new fish, or a harmful exposure has made your current tank unlivable. A backup tank can also be used for a hospital tank (when needing to treat one or some fish separately from the main tank).

Also, if a heater or a filter malfunctions, you can instantly replace it. To have a heater die in the dead of winter during a holiday, past closing hours, or just as you’re about to leave for work can harm and potentially kill your fish. Having a backup will keep your mind at ease, and if such a malfunction occurs, your fish won’t suffer from the delay.



For Uncycled Water: This is somewhat of a controversial item. Zeolite is ammonia absorbing media meant to be placed in filters. Companies market this as a media best used for brand new setups that haven’t been cycled yet (cycled—good bacteria built up over time that destroys toxic ammonia caused by fish waste).

In a way, this product is best for fish living in a cycling tank with ammonia. Instead of having to perform multiple water changes and adding Prime to detoxify ammonia and nitrites every two days, put some zeolite in the filter and it will keep your fish safe for about two weeks.

But many would argue that you shouldn’t have fish in a cycling tank in the first place. The risk of ammonia and nitrites spikes is always there, and you can’t predict when it will happen—in the middle of the night, at work, or at school. It will kill even the hardiest fish over time. So cycling with fish is very discouraged in the fish keeping community, and it’s best to cycle a fishless tank instead.

Disadvantages of Zeolite

The problem with zeolite is while yes, it will keep your fish safe for a few weeks at a time, it will also delay the cycling process. Ammonia is needed to start the cycle; after the initial ammonia spike, good bacteria will grow and break down ammonia into nitrites. Then after the nitrite spike, good bacteria will break that down into safe nitrates (as long as nitrate is no higher than 40ppm). If you start the tank right away with zeolite and 0 ammonia, your water is just waiting for ammonia so it can begin the cycling process.

I will not say that zeolite with delay cycling indefinitely. I have used zeolite in a new tank before, then replaced it with active carbon after a while. To this day it’s ammonia free, but this is probably due to the ammonia and nitrite spikes that occurred once the zeolite wore off (as well as before introducing zeolite in my filter). I think it also helped that I seeded a few items in the tank from an established one.

So it is possible to still have a tank cycled using zeolite, but it will take longer for the cycling process to start and it’s still just as risky as using Prime and performing water changes instead. I definitely encourage people to be patient and set up the tank four weeks (while occasionally adding a drop of pure ammonia) before buying its inhabitants.

Advantages of Zeolite

So why have this product on hand? Well, zeolite is great for an emergency tank that needs to be set up immediately. If you have a fish and you don’t have or know anyone with an established aquarium, at least the zeolite will make the water livable for the time being.

And while your fish is living in its new tank with zeolite, I would take your emergency backup accessories and begin a fishless cycle separately and simultaneously. Throw in some décor so once your backup tank cycles, you can transport the good bacteria (on the décor) into the new tank. The most important seeding item of all is the media/filter floss in the backup filter—this will be the most effective item to place in your tank once good bacteria has colonized on it.


Battery-Operated Air Pump

For Power Outages: This can be a lifesaver. A power outage may be an inconvenience to us humans, but it is life threatening for animals that depend on electricity to keep their homes livable. Case in point: fish and aeration. Unless you only have labyrinth fish (can breathe air), fish need plenty of oxygen in their water so they can breathe. How long a non-labyrinth fish can live in non-aerated water depends on the type of fish and how long the tank has been established, but in general you don’t want them to be in still, unfiltered water for more than a few hours.

Air-Driven Filters or Not

Battery-operated air pumps, as the name implies, does not rely on electricity. It will aerate your water (best to use an air stone) while your power is down. If you have an air driven pump, then this is an even better product, because that means you can run your filter and/or air stones, like you would normally do when you have power. Filtration not only provides aeration, but of course it also removes ammonia and nitrites through the nitrogen cycle.

If you don’t use air driven filters, only through a generator can you filter your tank. You could purchase an air driven filter and use that during this emergency. I’d recommend the box/corner filter, because you can merely pick up the filter media in your current filter and place it in the box filter, so you still have your biological filtration at work. But if you choose to only keep non-air driven filters, at least you can keep the oxygen up during the power outage with an air stone and air pump.

Large Setups and Multiple Aquariums

If you have a very large tank, I’d also invest in a large, much more effective air stone, such as the elongated ones. Also if you have multiple aquariums, I’d either buy a battery-operated pump for each tank, or figure out a way to share the pump among the tanks. These pumps can be in chain pet stores, but local fish stores almost always have them. Fishermen use them a lot when transporting their live catch.


Related Articles