They grow up to 3 inches and have a life span of 5-6 years depending upon care and maintenance. this fish is extremely good choice for any beginner hobbyist as it is very robyst and tolerant to wild variety of water condition, it’s a very hardy fish and on account of their exception active nature they are not appropriate choice and tank mates for passive and shy inhabitants as they are constantly on the move and can harass others in the tank which could cause problem in shy varieties of tank mates.
They are omnivorous and would eat anything that they are fed twice or thrice a day.
Partial water change of 25% every week would be recommended if the tank is not densely stocked.
It would be appropriate to have school of 7 or more Black widow tetra in a minimum of 25-30 gallon aquarium. in case of black tetra more fishes would make them more comfortable. the filtration system needs to be a high quality without creating much water turbulence as these fishes prefer slow water movement.
it would be appropriate to keep smaller size fish or larger size fish in the community tank along with black widow tetra as small fishes may become target of their fin nipping habits and stressed. these fishes are skilled jumpers it would therefore be necessary to secure the aquarium by covering it.
The good compatible tank mates are similar size tetras rainbow fish, larger rasboras, barbs and some dwarf cichlid, danios since they are hardy fish in a well maintained aquarium their health would not be of any issue.