Lump on leopard danio tail

Long time since posting....fish have been well. I have six leopard danios in my 100 litre tank, along with eight rasboras and a couple of old neon tetras. The leopards have been very well but I have now found one with a small pink lump towards the base of the tail and a slight degree of fin raggedness.
Difficult to photo because these fish are so fast. The lump is maybe around 3 mm in size, something like an insect-bite if it was on a human.
I have never had to treat my warm-water fish for finrot, if this is what it is; but I am not sure. I've not seen a pink lump like this before.
Ammonia, nitrite, zero ppm; nitrate currently around 10 ppm. pH can't give you that one at the moment, test kit has run out. Water temp 73-75 Fahrenheit (about 24C). Did a 30% water change yesterday, I try and keep the nitrate to no more than 20ppm.
Side issue: Persistent problem with hair algae, despite reducing light levels and food.

any chance of a picture?

Well I'll try tomorrow around lunchtime (I'm not free till then)....but the little blighters move at sixty miles an hour, very tricky to catch on camera!

They are fast little suckers! Lol

Here you go; not brilliant these took me twenty minutes to catch!
Hopefully you can see the pink blob on his/her tail.

I can see something but can't identify it because it's too blurry.

Yes I'm sorry for the blurring but unless I nail the fish down to a bench to take the photo, it's kind of difficult. I've already processed the photos with unsharp mask in Gimp to try and help with that. I might have another go later on...photographing, that is....

open the curtains (if it's day time) and have the tank lights and room light on and use the flash.

if you have a SLR camera you can set the shutter speed to 1/250, then click away.

if you can't change the shutter speed, see if there is a sport mode and set the camera to that. It should use a faster shutter speed that should help capture the fish without the blur.

I think my camera has a continual shot mode, I'll need to find it....I'm not much of a photographer, I'm afraid. Here's another one, but I'll keep trying...will try and post later.

Possibly a tumour or bacterial infection. How long has the lump been there for?

Tumours generally appear over a month or more. Bacterial infections can appear overnight.

If you have a spare tank you could move the fish into that and treat it with a broad spectrum medication that treats bacteria, fungus and protozoan infections. If you don't have a spare tank you can treat the main tank.

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To work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.

When you measure the height, measure from the top of the substrate to the top of the water level.

There is a calculator/ converter in the "How To Tips" at the top of this page that will let you convert litres to gallons if you need it.

Remove carbon from the filter before treating or it will adsorb the medication and stop it working.

Wipe the inside of the glass down with a clean fish sponge. Do a 75% water change and gravel clean the substrate. Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks.

Increase surface turbulence/ aeration when using medications because they reduce the dissolved oxygen in the water.

I think the lump has been there for a couple of weeks; it must have been very tiny to start with; I didnt notice it straight away. I'll look for a general purpose treatment as you say...there's no over-the-counter antibiotics here. If it's a tumour, don't know what will handle that (nothing much, really) but another water change, filters, etc certainly won't hurt. The fish is still very active and eating, so far so good; and the other five danios appear to be unaffected. Thanks for the input...I'll give it a go.

Danios are very hardy fish. It may not even bother him. Good luck!

That’s so weird!! Hopefully, water changes and good parameters will fix that thing up in a jiffy!! Belive me, they are very hardy fish!! I rescued mine from a guy on Craigslist, the tank was so bad, I had to do a 100% water change, and complete remodel! He is still very happy, and frisky!! Lol, your right, theses little things move so fast!!

Is it just me, or is your ZD a litttl bloated?

The fish in the picture is a female leopard danio that is full of eggs.

That’s cool!! So he will have little baby ZD’s?