Does This Look Suspicious - Molly Content

[Macko1968]

A brief background first as I know you folks like as much detail as possible.

155 litre tank
plastic plants, cave & tree stump type decor
Tetratec air pump powering a bubble curtain
Fluval 205 filter
full fishless cycle completed last Friday
stocked last Saturday with 9 zebra dannios, 5 cherry barbs, 3 black mollies & 3 silver mollies
2 barbs died on Sunday morning, no sign of any disease
All other fish lively, eating well, swimming round no sign of any distress
water readings constant 0ppm amonia, 0ppm nitrite & nitrate just reached 10ppm today. PH is 7.8 and we have hard water.

I noticed tonight that one of the silver mollies has a patch approx 1.5mm diameter on her tail that is not fully translucent like the rest of it. It's not noticable when she is swimming but when she stops it can be seen. It's not a fluffy spot, doesn't appear to be raised or depressed, no redness around it and no sign of any fin-rot. After about 80 shots this is the best picture I can get of it;

Can anyone let me know if I should be worried about this?

 

[Bigbadbaz]

Cannot see your pic as I am work, treat the tank with Melafix to aid regeneration, may be she has rubbed up against something or been fighting.

 

[LauraFrog]

I don't know what it is or how serious it is, but mollies are fairly prone to this problem when kept in freshwater. If the water is extremely hard you can get away with it but otherwise it's best to add some salt. Even 1 teaspoon/gallon will make a difference. I'm not sure if the barbs would like it though. Danios are also okay in hard water, but I don't think barbs like it so they probably wouldn't appreciate salt.

 

[Athena]

External flukes often look like that in finnage - they are not very noticeable until the light shines through the fins. They look like tiny, blurred white pinhead spots - and often you will only see a couple (it's not like whitespot that covers the fish).

Was the fish like this when you bought it or did you only just notice the spot?

Obviously, it's difficult to say 100% from that photo if this is definitely flukes or not but it's the only thing that sprang to mind when I saw the pic. Someone else might know another reason for it...

Anyway, to treat flukes you can use Sterazin after a partial water change. Make sure you are not overfeeding, too.

Regards - Athena