Newt Larvae Set-up questions

I have triturus dobrogicus larvae ranging from .5 inches to 3.5 inches and was wondering if the 2 inch plus newts could be in at 10-15 gallon aquarium with a filtration system and what kind of filtration is best. I currently have them in critter keepers and they are nipping each others gills and tails too much. So for starters I am going to use a 15 and a 10 gallon to house the 1.5 inches and up.

Also how much could I cut down the water changes by with a filtered aquarium? Like 20% daily and 50% every other day? I was thinking wisper filters or undergravel filters. Undergravel filters cost more but if they are extremely more effective I would use them.

Also could I put small feeder guppies in the tank with the larger larvae for a continious food supply so there would be less nipping. I feed them frozen blood worms and chopped earthworms for the larger newt larvae?

Should I have live plants in the tanks? Are they very benificial for newt larvae?

For filters, I would recommend an in-tank waterfall filter rather than the kind that hangs on the back of the tank. The 3.5-inchers will be morphing very soon, and at that point you need to seal the tank like Alcatraz.

How much water you need to change really depends on the number of animals and size of the tank. Five larvae in a 15-gal tank might need only a few gallons changed a couple of times per week, while 20 large larvae in a 15-gal might need 50% changed daily to keep the ammonia under control.

Providing plenty of live food and loads of live plants and other hides will cut down on nipped extremities.

Thanks for the feedback. Wont that kind of tank catch thier tails though? Maybe I could put a piece of foam or something infront of it. Any other suggestions?