Once a knife fish gets used to black worms it is really hard to get them to eat other foods.
If the glass knives you can get are the same size (10-12 cm) you could fit a couple more in the tank. We sometimes keep as many as five in a 15-gallon tank, as long as the filtration keeps things in balance. Its a trade off between ideal population size and keeping a very social fish happy. As other members have mentioned, these fish need companions or they become stressed.
We found in our experiments that as soon as we move a glass knife from a group tank into an isolation tank, the size of the electric signal starts to decline the first day and gets smaller for the next two weeks until it is around 20% of its original amplitude. A sure sign of an unhappy fish.
If the glass knives you can get are the same size (10-12 cm) you could fit a couple more in the tank. We sometimes keep as many as five in a 15-gallon tank, as long as the filtration keeps things in balance. Its a trade off between ideal population size and keeping a very social fish happy. As other members have mentioned, these fish need companions or they become stressed.
We found in our experiments that as soon as we move a glass knife from a group tank into an isolation tank, the size of the electric signal starts to decline the first day and gets smaller for the next two weeks until it is around 20% of its original amplitude. A sure sign of an unhappy fish.
