Red Streak On Silver Shark

[mobeyone]

I have just noticed a thin red streak on one of my silver sharks, what is this?

 

[WILDER]

Need size of tank in gallons or litres.
How many fish and which type.
Water stats in ammonia,nitrite,nitrate, and ph.
Where is the red streak as it can be due to poor water quality, septicemia.

 

[mobeyone]

90l tank, fish as follows:

1xplec
3xneon tetra
2xgouramis
3xcorby
2xguppies
2xsshark

Just the one at the minute and its on the bottom fin, a very thin line running across.

Water is clear and all levels are fine now.

 

[WILDER]

Septicemia then need a good bacterial med.
The tanks too small for the bala sharks they need about 90 to 120 gallons.