Dark spots appearing

[ScareCrow]

Hi all,

I've had a pair of kribs for about 4 months and have noticed in the past few weeks some dark spots appearing on the underside of the female (picture attached). Both fish also seem to be more nervous.
I've not changed anything in the tank since I got them. There is plenty of cover (although no floating plants, which I think might help with the nervousness) and there's a cave that they regularly spawn in (they are spawning as I write this).
I've had this species before and never noticed this happening before but talking to a friend his pike cichlids display the same symptoms for a while but eventually the spots disappear. I'd be interested if anyone knows what it is or what causes it?

Tank parameters are :
Ammonia 0ppm
Nitrite 0ppm
Nitrate 5-10ppm (I'd be surprised if it is actually that high as I have pothos growing emersed)
Temp 24
TDS 320

Water change of 25% 2x a week. There are no other fish in the tank.
I feed a mix of TA Aquaculture granule blend, Astax granules, high protein granule, aquacare topical granule and grindal worms.

Thanks in advance for your time and suggestions

 

[Simon Cole]

Can you add two side-on photographs please?

 

[ScareCrow]

Hi Simon, thanks for your reply. I've attached some photos of both sides. The spots aren't very visible from the side, apart from on the left pectoral fin.

 

[ScareCrow]

I managed to get a slightly better shot of the patches on the underside. They appear to be slightly darker than before but some appear to have disappeared.

 

[Simon Cole]

How incredible!
@Gill - take a look at this
I think we can see some sort of pigmentation response because you fish is on heat.
I was worried initially it was some kind of subcutaneous defect where we would expect the liver, but clearly not, because its on the fins. Cancer can also be ruled out because that stays in one place.
Good news I reckon. But please could more members respond.

 

[ScareCrow]

Thanks Simon. It is very odd I'd heard of 'black spot' years ago. It's caused by a parasite but it has quite a complicated life cycle, which requires a bird, so I ruled that out!
In regards to your comment, I have been trying to restrict their spawning. I've removed bloodworm from their diet, as that was triggering them to spawn quite frequently. They're both young fish and not great parents. So I'd like to grow them up (hence the use of high protein foods) before trying to spawn them purposefully. I wonder if it's something that's hormone related.

 

[Simon Cole]

Black spot disease can be linked to trematodes - a kind of parasite. But your fish has slightly larger patches and it appears localised. If it looks like it has been peppered, then you have the trematodes. But I think your fish looks quite healthy right now.

 

[ScareCrow]

I got a better shot of her right side so have attached in case anyone is interested. I've also noticed that the patches on her left side and pectoral fin have gone.

 

[Simon Cole]

Great news. Have you named her yet? Something like Patches would be a great name.

 

[Gill]

I agree with Simon, looks nothing more than a change in coloration of the fish. I would have been worried if they appeared to be raised.

 

[ScareCrow]

Thanks to you both.

I'm terrible at coming up with names, so I'll take your suggestion, Patches it is.

 

[mort]

I've not seen this before but it wouldn't surprise me if this is something to do with mating as well. I'd be more enclined to suggest a reaction to physical damage, ie from rubbing when laying eggs or perhaps the male biting the belly to induce spawning. We see similar damage on marine clownfish and it's called hyper melanisation.