Red tail shark

[Gneal]

Had a red tail shark for 9 months, all fine.
Was kept with 3 cardinal tetra, 2 rummy nose tetra. 50 litre tank.
Last week we added 2 more rummy nose and 2 penguin tetra.
Last couple of days his dorsal fin is clamped and he rubbing against gravel.
Any ideas? All other fish are fine.

 

[ZxC]

how big is it? 50 liters is way too small for a red tail.

do you have an ammonia, nitrite and nitrate test kit?

 

[King Fisher]

I second Z. Your red tail should be in a 190 liter upon adulthood.

Look for small white dots on his skin similar to salt grains. If not ich then it could be parasites.

 

[Gneal]

Thanks will keep a close eye on him.
Is uk litres same measurement to US?

 

[King Fisher]

If 190 liters is 50 gallons

 

[Autumnsky]

Red tail sharks (RTS) really need to be in a 75G / 283 liters at adulthood. They get 6+ inches or 15.25 cm. They really use a large space for territory. Mine was in a 72G and I made sure to add what I called race tracks in figure 8 design so she could swim around the bottom of the tank and also a figure "8" about 1/4 to 1/3rd from the bottom of the tank, at a slightly different angle. All fish respected the RTS and moved out of the way when she was in her "shark" mode - patrolling all around her territory.

So please consider the age of your fish as well, as they are juveniles they are less aggressive. But at they start reaching maturity they get especially aggressive and will often menace a fish. Especially so when there isn't a sufficient area for them to have their territory. And room for the other fish to get away from the RTS to be in their own space.

 

[King Fisher]

I'll correct myself from my last post.....I meant a 55 gallon tank that's 4 feet long or a 4 foot tank like a 75g as autumn pointed out.