GloFish Tetra has scales missing and black spots on its fins

Hello! I’m new to the hobby and had my tank running for a month now.

I apologize in advance for the huge text, but I’d rather explain everything in detail and hopefully I can have your much needed help.


Here’s a bit of backstory: When I first got my aquarium I was, unfortunately, quite uneducated on it - I didn’t know about the nitrogen cycle for example.

As it all started growing on me (after i got three tetras to keep me company as I had just moved to another country, far from family or friends) I did extensive research and bought the equipment I needed to keep them healthy and safe, so I assure they’re not neglected at all.


About the tank:

I have three juvenile GloFish Tetras on a 10 gallon tank (which the lady at the pet store told the misinformed me that was plenty of space - but I’ll be moving them to a 30g when possible, as I intend to have more fish in the future) and it didn’t cycle completely yet.

I test the water twice a week and last time the ammonia level was 1ppm, nitrites 0 and nitrates 0. I’ve been changing 20% of the water every other day to reduce the impacts of ammonia on them.


About the fish:

Both my yellow and green tetras are very active, responsive and eat well, though they have been extremely aggressive towards my red tetra. Since the past week the red (Gummy) has started to behave more shy and hide from its mates, and yesterday I realized he had a number of scales missing (probably from nibbling). He had been eating less and less (as he was constantly attacked when he swimmed for food) and today he didn’t eat at all, even when the defrosted brine shrimp floated in front of him.

I bought API’s aquarium salt and added a light portion on the tank with the intention of preventing infection on Gummy’s sores. That’s when I realized he had suddenly developed dark spots on his fins and a black spot on his side, which looks open but was hard to get on camera. He also swims mostly close to the top of the aquarium now.

I am very concerned with Gummy and with the disease spreading to the other two guys. I care a lot for these fish and don’t want to see them suffer at all. Is there anything that you could help me with? Thank you so much!

Hi and welcome to the forum

How often and how do you clean the filter?

If you have an ammonia or nitrite reading in the tank, you should do a 75% water change and gravel clean the substrate every day until the levels are back down to 0. You should also do a 75% water change and gravel clean the substrate once a week or if the nitrate level goes above 20ppm.
*NB* Make sure any new water is free of chlorine/ chloramine before it's added to the aquarium.

You do water changes for 2 main reasons.
1) to reduce nutrients like ammonia, nitrite & nitrate.
2) to dilute disease organisms in the water.

Fish live in a soup of microscopic organisms including bacteria, fungus, viruses, protozoans, worms, flukes and various other things that make your skin crawl. Doing a big water change and gravel cleaning the substrate on a regular basis will dilute these organisms and reduce their numbers in the water, thus making it a safer and healthier environment for the fish.

If you do a 25% water change each week you leave behind 75% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

Fish live in their own waste. Their tank and filter is full of fish poop. The water they breath is filtered through fish poop. Cleaning filters, gravel and doing big regular water changes, removes a lot of this poop and makes the environment cleaner and healthier for the fish.

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You have 2 different species of tetra. The fish in the top picture looks like a coloured/ painted red eye tetra. The 2 fish in the bottom picture look like coloured/ painted black widow/ skirt tetras.

All tetras should be kept in groups of at least 6 (preferably 10) or more of their own kind. Having 1 or 2 individuals of a schooling species causes a great deal of stress to the fish and they can act aggressively or timidly. When you get the bigger tank, you should look at increasing the numbers of each, or getting rid of them and getting something else.

I called the fish coloured/ painted. The fish appear to be artificially coloured by people and look slightly different to the glofish sold by the company at the link below. You will have to contact the pet shop where you bought them from to find out if they are genuine glofish or coloured/ painted by people. If they are coloured/ painted by people, then I don't recommend getting more because the colour eventually fades. It's also quite a bad practice where the fish are either painted with paint or injected with a coloured dye. If they are genuine Glofish, then you can get some more.
https://www.glofish.com/meet-glofish/glofish-gallery/

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Have you added anything to the tank in the last 2 weeks?

The spots look a bit like whitespot (Ich). The safest way to treat this is with heat. You raise the water temperature to 30C (86F) and keep it there for 2 weeks. Then lower the temperature back down. If the water is less than 27C now, then only raise the temp by 3C per day until you get to 30C.

Do a big water change and gravel clean the substrate before increasing the temperature.

Increase aeration/ surface turbulence to maximise the oxygen levels in the water.

The following link has information about white spot. The first post on page 1 and second post on page 2 are worth a read.
https://www.fishforums.net/threads/what-is-ich.7092/

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Salt isn't the best thing for tetras or other fishes that come from soft water.

The following link has information about what to do if your fish get sick. It's long and boring but worth knowing. I recommend printing it out and reading it in bed to help fall asleep.
https://www.fishforums.net/threads/what-to-do-if-your-fish-gets-sick.450268/

Hi! Thanks so much for the reply!


For the filter, I changed the cartridge every time it indicated it needed change (once every 15 days so far). I didn’t clean inside yet. I’ll do the water changes for sure.


The fish in the first and second photo are the same, they are gmo White Skirt Tetras, and though they don’t look as bright in the picture they glow like highlighters under blue led. (Picture attached)

I’m confident these are genuine GloFish as I got them at PetSmart and the companies are partners.


About adding new stuff, all I added was a new small filter, enough for 5g, because the water started to look a little cloudy. Now it’s clear again, so I consider it a good purchase.


About the temperature, I saw white skirts can stay at 70-90F, but the glofish website recommends between 72-80F. The aquarium is around 78F now; will it be safe to raise the temperature further than 80?


I really, really appreciate your help. I’ll be reading the material you sent me and will keep searching for a solution to keep the boys as healthy as I can.

Tetras do better at the lower end of their temperature range but to treat white spot you need to get the temp up to 86F. If you raise the temp a couple of degrees per day, the fish should be fine at 86F. Just make sure you increase aeration/ surface turbulence to maximise the oxygen levels in the water.

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Companies sell filters for aquariums and they want you to keep buying their products. So they tell you to replace cartridges every 2 weeks or whenever. This is good for the company but screws up the filter bacteria and the fish.

Most filter pads/ cartridges have carbon (black granules) in and this is not necessary in most aquariums. You can usually open the cartridge and tip the granules out and throw them away, then wash the cartridge out and put it back in the filter.

You can get round/ cylindrical sponges for some brands of internal power filter. These sponges have a hole through the centre of them and you can put the sponge over the intake strainer of most external power filters. The sponge can be removed each week and washed in a bucket of tank water, then put back on the intake strainer.

You can buy rectangular sponges for various brands of filter and use a pr of scissors to cut them to fit into your filter instead of using the filter pad/ cartridge. Then you wash the sponges out in a bucket of tank water when they get dirty.

Thanks again! I made sure to start slowly rising the temperature, around 3 degrees a day. I’ll be looking for the filters you told me about, they’re a way better deal.

On a quick update, i got a little quarantine tank for Gummy, where I started treating him with API’s super ick cure. The white spots disappeared fast but, considering the big wound on his side, I’m still not sure he’s gonna make it. He looks stable and less stressed, and even ate a little this morning. Should I get him some antibiotics? Would it be too harsh on him to treat his wounds while treating ICH too?

PS.: I’ll medicate the big tank as well to prevent the parasite from contaminating the other two guys.

Hello,

I am new to the forums and wanted to chime in because of your Glofish. I just love them, even though people don't really give them a chance. I have a 29 gallon with two Glofish barbs and a Glofish shark. I am also running a 75 gallon with 4 large Danios, 6 Glofish tetras, 1 Glofish shark and two cory pandas. I have had 6 Glofish for 3 years all tetras and they are all flurishing and are the diameter of a ping pong ball. But not fat...lol. I have learned it's all about water change. I have never had an issue with nirates or nitires. The ammonia is cut and placed in the HOB Aqueon filter and filters rinsed every 2 weeks and fully changed at a month with cold water. With water temp around 81-83 F. I only use two chemicals ever. I found the more chemicals I used the more complaicated things started to get.


Before your water change wash, wash, wash everything before and after handling your fish and inside the tank. Bacteria grows EVERYWHERE and rapidly that can be transfer back into your clean tank from your net to catch them or just your hands. Even towels you use from laundry. With my plants I soak them in a warm to got bath and then I use dawn dish soap very, very little....like a drop or two on a lite soft bristle brush or my hands to scrub and them I rinse, rinse, rinse and rinse some more. Just to make sure it doesn't contaminate your water or make your fish sick or die. Dont soak anything in chemicals only water. I change the water every 2 weeks 50% half change. Sand substrate with no natural plants. Ph. has always been around 7.8 and now I switched to a balancer at 7.0 ph. So far everyone is happy and healthy! I hope that helps. Good luck!!

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KellyGrobe said:

PS.: I’ll medicate the big tank as well to prevent the parasite from contaminating the other two guys.

Click to expand...

There's no point adding medication and using heat.

I recommend heat treatment because it's safer for the fish and for you. Most Ich/ white spot medications contain Malachite Green (aka: Victoria Green), which causes cancer. Raising the temperature to 30C (86F) kills the white spot parasites without the use of chemicals.

The following link has information about white spot, including different treatments. The first post on page 1, and second post on page 2 are worth reading.
https://www.fishforums.net/threads/what-is-ich.7092/

I would move the fish back into the main tank. Do a big water change and get the temperature up. Then let it run for 2 weeks before lowering the temperature.

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re: the wound on his side. I can't see that. If you can post another picture that clearly shows the problem I might be able to offer more info.

Cottonball said:

I have never had an issue with nirates or nitires. The ammonia is cut and placed in the HOB Aqueon filter and filters rinsed every 2 weeks and fully changed at a month with cold water. With water temp around 81-83 F.

Click to expand...

Hi and welcome to the forum

If you use ammonia adsorbing granules, that will prevent nitrite and nitrate from occurring. It will also prevent the filter from developing beneficial bacteria that normally convert ammonia into nitrite and nitrite into nitrate.

You can recharge most types of ammonia adsorbing granules by soaking them in salt water for 24-48 hours.

If you use ammonia adsorbing granules, you should replace/ recharge them every week to make sure they aren't full and can remove any ammonia produced.

Is it my phone? I’m not seeing white spots, I see black spots. If they are black, I would lean towards ammonia burns. I just don’t see the ich. With the open wound, I would continue using the aquarium salt. If it doesn’t heal then you will need an antibiotic. I recommend Kanaplex. Good luck!

Colin_T said:

re: the wound on his side. I can't see that. If you can post another picture that clearly shows the problem I might be able to offer more info.

Click to expand...

Here’s a picture of the wound taken before medicating him. It’s deep and black, and looks very bad. There’s a white thing inside, I’m afraid it would be part of his spine showing or something. His gills are very red and swollen, and that’s why I thought of using antibiotics.
Do you have any recommendations? API’s fin & body cure, Melafix maybe?
That’s my main concern at the moment, what makes me think he has a low chance of surviving. Thanks so much for helping me.

I see the white spot now. I still believe your fish is suffering from ammonia poisoning too. The decision is which do you treat first. Methylene blue helps with ammonia poisoning. It can also help with ich. Since fish is in bad shape, I would do methylene blue dips and get some Kanaplex ASAP. At this point he needs an antibiotic to fight infection. The Kanaplex is an antibiotic. You can get it at PetSmart. The methylene blue will have instructions on the bottle on how to do dips. Keep us posted. Good luck!

The black patch looks like a hole in the fish's side. If this is the case, you need to find out what caused the hole. It is either a bite or a bad bacterial infection.

If it is a hole, I would not remove the fish from water because it will get air inside its body via the hole.

I would look at using anti-biotics or Methylene Blue, both of which kill bacteria.

Hi! Thanks so much for the reply!

I found GloFish fascinating, and I love to see how science worked on them; glad to know we share the same taste!

I was doing frequent, but very small water changes and I saw there were no big results. Today, after a bigger change on the 10g tank, it really improved the water quality.

After reading your text, I tried to be even more sanitary than before; I don’t want to see my fish going through any trouble that soon! You gave me a very simple but needed tip that makes all the difference and I’ll be thinking much about. Glad to know your fish are doing well, I hope they’re even better in the future. Thanks!