This strain of Tilapia is a hybrid strain. It was created by cross breeding and a male Blue tilapia (Oreochromis aureus) of the ND-1 Tilapia family line with a female Nile tilapia (Oreochromis niloticus) of the ND-2 Tilapia family line.

The ND-1 and ND-2 Tilapia family lines were both created by selectively line breeding Tilapia fish with desirable characteristics.

ND21 tilapia has several fine qualities:

• The ND21 Tilapia is fast growing and the growth rate is comparable to the growth rate of pure bred Oreochromis niloticus. The ND21 Tilapia strain grows quicker in colder water 22-25 °C (72-77 °F) and more slowly in very warm water 29-31 °C (84-88 °F).
• The ND21 Tilapia is a docile strain and less prone to jump than most other strains. These qualities make the fish easier to handle when you need to sort, harvest etc.
• The ND21 tilapia is a mono-sex tilapia. When breeding a male Blue tilapia (Oreochromis aureus) of the ND-1 Tilapia family line with a female Nile tilapia (Oreochromis niloticus) of the ND-2 Tilapia family line, all the fry will be males. Some females might occur due to the risk of foreign genetic material and the average proportion of males is therefore 98 percent. Two percent females are not enough to affect the productivity negatively and can therefore be seen as acceptable.

ND21 tilapia has the same resilience as pure bred Oreochromis niloticus to Streptococcus infection.