Guppy fins can grow back providing the original cause has been resolved. Fin Rot must be treated before fins will grow back. Guppy fins can take anywhere from a few days to start to show signs of healing to around 3 months to be fully grown back
Everyone seems to love a guppy. They have been popular in our hobby since the 1960s when hobbyists first started selectively breeding them to give us the wonderful array of colors and tail shapes we see today. Guppies are friendly, colorful, and hardy, making them an ideal ‘community’ fish.
I first started keeping guppies over 30 years ago when I was given a 10-gallon aquarium and a small group of guppies. Over the last 3 decades, I don’t think there has been a single day when I didn’t have at least one tank full of guppies in my fish room.
What Causes Guppies To Lose Fins
The most common cause of guppy fin loss is fin rot. Fin rot is a bacterial infection that is most often caused by poor water quality in the guppy aquarium. Fin rot can set in very quickly if the guppy’s immune system is compromised or the water they are living in is dirty.
Occasionally, one fish will nip at one another’s fins, or you may get a fish that is bullying another fish, continually biting the weaker fish’s fins. Much like when we cut ourselves, the area of fins that have been nipped is the perfect place for bacteria to get in and start to take advantage of the guppy’s injury.
What Is Fin Rot
As mentioned above, fin rot is a bacterial infection. Fin rot is caused by a small number of different bacteria, including Aeromonas, Pseudomonas, or Vibrio bacteria.
Fin rot is extremely preventable but can be tricky to cure. The sooner treatment starts the easier it is to cure and for the fins to grow back. If fin rot goes untreated it can cause irreversible damage to a guppy and in extreme circumstances, it can actually kill the guppy.
What Causes Fin Rot?
The most common cause of fin rot is poor water quality. Studies have shown dirty aquarium water contains a lot more bacteria than clean aquarium water. Some of these bacteria may cause fin rot.
When one fish is bullying another fish, or if guppies are overcrowded in an aquarium, they may nip at each other’s fins. These ‘open wounds’ are the perfect way for bacteria to enter the guppy’s system.
What Are The Symptoms Of Fin Rot?
In its earliest stages, fin rot often goes unnoticed. The very edges of the fins start to discolor and turn a milky white or black color. As the disease progresses the edges of the guppy’s fins may take on a frayed or torn appearance. Again, this slight fraying often goes unnoticed and untreated.
As the disease spreads further up the fins, the small pieces of the fins start to die and drop off the fish, leaving behind very jagged and torn fins. This is the point most fish keepers begin to notice something is wrong.
If left untreated the disease will continue to spread up the fins, eventually reaching flesh and bone which may take on a red, inflamed appearance once the fin rot reaches it.
If fin rot is left untreated for long enough, secondary infection can set in. Other strains of bacteria and fungus can quickly take advantage of the guppy’s poor situation. I was once given a guppy by a neighbor that was so poorly affected by fin rot that its tail was non-existent and most of its body was covered in fungus.
Sadly, on that occasion, I decided the kindest thing to do was to euthanize him.
How To Treat Fin Rot?
When treating fin rot, the quicker you start the better. If left too long, fin rot damage may be irreversible.
Before you begin treating the fin rot, test your aquarium water using a good quality test kit. I have had great success using the Master Test Kit by API (like this one I bought from Amazon). The kit is easy to use, gives results quickly, and is pretty accurate.
The ideal parameters you are looking for when you test your water should be close to the following;
- Ammonia – 0ppm
- Nitrite – 0ppm
- Nitrate – 40ppm or less
- pH – 7.2 – 8.0
- Temperature – 72°F to 80°F (22°C to 26°C)
If you find your parameters are drastically outside of those listed above, consider rectifying them as soon as possible.
For high levels of ammonia, nitrite, or nitrate, I would suggest you carry out a 50% water change immediately. Repeat every day until parameters are back where they need to be. If you find your pH is not between 7.2 and 8.0, consider carrying out a water change, providing you know what the pH of your tap water is. There is no advantage in carrying out a large water change if the pH of your tap water is very low or very high.
If you check your aquarium water temperature with a thermometer and discover it is either below 72°F or above 80°F, check the settings on your heater. If necessary, adjust your heater settings or replace the heater. My article titled Do Guppies Need A Heater? may help.
Once you have made sure your water is in good condition, start treating the guppies fin rot. Over many years of treating fish, I have found that Marcin by Fritz is the best treatment for bacterial infections including fin rot as well as the fungus that may have taken advantage of the sick guppy.
Treat according to the instructions and your guppy should react well to the treatment.
How To Prevent Fin Rot?
In my experience, preventing fin rot in the first place is much easier than trying to treat it. The number one factor when it comes to preventing fin rot is good aquarium maintenance. Carrying out regular water changes (I like to change maybe 20% to 25% of the aquarium water in my guppy tanks each week) as well as keeping filters clean and running will seriously reduce the chances of fin rot setting in.
Feeding your guppies good quality food will keep their immune system in top condition and allow them to fight off any bacterial infections before they have a chance to take hold. Over the years I have written countless articles on feeding guppies, but this one is titled What Do Guppies Eat? probably covers most of what you need to know.
Another way to prevent fin rot in the first place is not to overcrowd your guppy tank with fish. Guppies, like so many livebearers, can quickly multiply and before you know it, overrun your tank. If you keep guppies, have a plan for what to do with all the babies they will undoubtedly have.
How Long Does It Take For Guppy Fins To Grow Back
Once treatment for fin rot has begun and the infection has cleared up, a guppy’s tail will usually start to show signs of regrowth within just a few days. After a couple of weeks, the growth will be really noticeable and hopefully, after 2 or 3 months, the guppy’s tail will be back to full health.
Obviously, time scales very much depend on how bad the fin rot was. If the tail has completely disappeared, it may never grow back properly.
Fin rot can be very nasty, but if we act quickly and treat appropriately, a guppy’s fins and tail can grow back. After a very bad infection, the fins may not grow back to their former glory, but hopefully, they will still be full of the color we love.
Keeping our guppy’s water clean and feeding them good quality food are the best ways to prevent fin rot from setting in in the first place.