Dwarfed cory?

[Ciciwarriner]

I have had a group of corys for about a year now and one of them hasn't grown at all. This little guy is about half of the size of the rest of them now and has never had any development of his barbels either. Anyone know what could cause this or if it is just a genetic thing? He seems happy and healthy and i see him eating quite a lot.

 

[Colin_T]

Usually caused by internal parasite like worms and or gill flukes. Deworm the fish and see if it improves.

Section 3 of the following link tells you about treating intestinal worms in fish. Roundworms are the most common and you can use Levamisole to treat them or if you can find Flubendazole, it will treat round and flat worms as well as gill flukes.
Praziquantel will treat tapeworm and gill flukes.

What to do if your fish has Stringy White Poop.

Fish do a stringy white poop for several reasons. 1) Internal Bacterial Infections causes the fish to stop eating, swell up like a balloon, breath heavily at the surface or near a filter outlet, do stringy white poop, and die within 24-48 hours of showing these symptoms. This cannot normally be...

www.fishforums.net

 

[Naughts]

has never had any development of his barbels either.

This is probably due to repeated exposure to bacteria from the gravel substrate. It cause the barbels to erode. ’Cories’ on sand tend to do better in this regard.

While you have gravel you could try more thorough and frequent gravel cleaning with a syphon. It looks like you need to change more water more frequently too. 50% weekly should keep the water clear and nitrates low.