Keep the ph at 7 or just below keep the temp high for tigs and don't feed any sea food to the tig until it gets past 12 inch lots of info you can read about tigs floating around right now about tigs so it shouldn't be hard to find what you need about them
What size tank was you thinking about putting the lince in please don't say you are building a tank for the lince as it will need that big tank the day you get it
Lince are never imported below a size of 12 inch and the death rate when shipping is very high as much as 50% due to the size
I wouldn't eve think about putting a lince in a tank smaller than mine 8 x6 x 3 and even that I am beginning to think is to small
People told me before I got mine that they grow slow that maybe true if you put them in a tank that's way to small but a good size tink like mine my lince has grown 4-5 inch in a year
Lince are a great fish but please don't put it in a small tank it's just not fair I would sell mine if I could find someone with a tank big enought to house mine for life but I feel even to try to move mine now would kill it
As for feeding a lince they eat anything when settled prawn meal worm pellets and anything else you want to feed it
They are a very fast and active fish that never ever stop moving which does piss some other fish off
The lince is not aggressive in anyway it very gentle and won't even try to eat fish much smaller
They do take a long time to settle in it took mine a month to start feed even after it was feeding in the shop that was holding it for me
On the whole the lince and tig are both my fav cats by a long shot if you have the tank space
Where did you find someone importing them at that size? The smallest Lince I've ever seen imported was around 7" and they are extremely rare at that size. Most available are 14-16".
Tigrinus generally don't gorge themselves like TSN's. You should not be feeding brine to shovelnose as juveniles...it's just too small and also is usually intended for saltwater fish. For small Tig's live blackworms/frozen blood worms work pretty well.
Do you have any pictures of any of these fish, I find it very hard to believe that you have a Lince cat under 7", let alone 3" considering I've never seen a single importer bring them in at that size or mention them even being available at that size. Are you sure that the fish someone is listing isn't just a pictus catfish?