There are some things you just plain need when you have an aquarium, like water conditioner, fish food, and your python gravel cleaner, but there's a handful of things people don't consider until it's an emergency and that can be a problem for your finned friends. It's important to have a few key medications on hand in case you run into an issue because most fish diseases are simple to treat if caught early. Home aquarists rarely run into issues with disease, which means that most don't spot the symptoms until they've lost a fish or two, and by that point, they have a full-blown infection in their aquarium.
Your fish are trying to tell you something
There's a handful of signs that are universal among fish that act as indicators that something is wrong. These are the first signs that something is wrong with your fish.
Loss of appetite
While not all fish will exhibit all three of these traits, there's a very good chance you'll see two of the three, regardless of the species. For clamped fins, pay attention to see if your fish is holding their fins against their body, or in the case of angelfish, folded down rather than proudly displayed. A great indicator is your fish's tail fin as fish rarely close their tail fin. Loss of appetite is fairly straight-forward. If your ravenous little fish have lost their appetite for more than one feeding, something is likely amiss. Lastly, watch for irregular behavior. Is your pleco out during the day when he only comes out at night? Is your electric yellow cichlid hiding when he's normally out strutting his stuff? Any type of irregular behavior is a quick indicator that something is wrong. Tetra has a fantastic post detailing fish diseases and what they look like, take a moment to check it out as we're not going to get into disease specifics.
The most common disease you'll run into is ich. Think of ich like fish fleas that can kill your fish if left untreated. The great thing about this disease is that it's really easy to treat, and you can fight it off just as quickly as it sets in. Rid-Ich Plus treats ich and a handful of other less common external parasites as well and is good for both fresh and saltwater fish. While it claims to help fight ungal infections because it contains malachite green, there are better medications for that. Another great point is that this medication doesn't expire. Make sure the cap is on tight, put it in a cool place and you're good to go.
One caution is when using it with scaleless fish or tetras. Make sure you start with a half dose, and if you see that your fish aren't in distress because of the medication, you can increase your dosage. Historically, I've only used this medication at 50% strength with sensitive fish, and it's worked great, it just takes a little longer to wipe out the infestation.
This is your goto for bacterial infections. Seachem makes a fantastic range of medications, with two of the three items on this list being theirs. Kanaplex is an anti-biotic that is absorbed through the fish's gills and skin, which makes this a great option if your fish has stopped eating. I used to use this as a preventative when I imported fish, and it's effective at fighting off fin-rot and columnaris. Kanaplex does have a long shelf life, about 2-3 years, and the expiry date is clearly labeled by Seachem. No cautions with this medication, just use as directed when needed. Kanaplex has a permanent place in our fish room.
This medicine is really effective at dealing with internal parasites. Metronidazole, "metro" for short, should be kept on hand if you're keeping cichlids who are susceptible to either lateral line disease, or hole in the head disease. These are actually different names for the same disease, as it's longer name is Head and Lateral Line Erosion disease caused by a parasite called Hexamita. There are a variety of reasons why this disease can take hold, but sometimes it can be caused by poor luck. One of our breeder altums started showing signs of lateral line disease, and this fish was in a tank with near perfect water parameters that was also being dosed with vitamins. Of the twelve altums in the aquarium, it was the only fish to show symptoms.
Metro can be added to the aquarium water, but I've found (as have others) it's more effective if ingested. Foods infused with metro are your best bet for fish that are beginning to show signs of infection. You can also buy Metroplex by Seachem and mix it into foods of your choice. Metro is a very safe medication, and I've fed fish metro infused foods for up to two weeks as they healed.
Old wives' tales
Salt - while effective, 99% of people don't use it properly. Salt alone will not help clear up infestations in an aquarium and by the time most people notice the problem, medication is required to get the disease under control.
Water changes - yes, what likely caused the issue was poor water conditions that need to be corrected, this will not cure your fish. There are some old-school hobbyists that claim that any disease can be cured by clean water, which simply isn't true. If a disease has taken hold, both the condition and the underlying cause need to be treated.
Grab a few meds as insurance
While the odds are you'll never run into a problem with disease, these medications will cover 95% of the diseases most aquarists encounter. Grab these meds, tuck them away, and enjoy your fish tank with a little extra peace of mind.
Leave a comment, a question, or even a contradiction down below and we can learn together.
Andrei Vexler is an aquarist with over 20 years in the fish hobby. Having run a fish room with over 700 freshwater and saltwater aquariums, Andrei found his passion in South American cichlids, particularly Altum angelfish. Growing and wholesaling angels to the GTA and the surrounding area, he shares his years of experience in his blog for advanced aquarists.