Typical LFS/LPS feeders that are offered...
Goldies, RosieReds & Guppies.
Goldies & Rosie Reds, why are they considered bad feeders?
1)Once most fish destined to be feeders are raised beyond growout they are placed in abhorrent holding tanks, shipped in severely overcrowded conditions and it is just more of the same at 95% of LFS/LPS holding tanks.
These conditions are prime for disease & parasites, the average feeder is a bio-hazard with fins.
2)Goldies & Rosie Reds, are considered coldwater fish and being such they have higher levels of fat, fats that are slightly different from a tropical and not as digestable by a tropical once fed.
Also, they contain thiaminase, this will cause a thiamine defieciency in your tropical and can lead to health problems.
3)Goldies are fish with a relatively large bodymass, if they stay in the tank for long they contribute significantly to the bio-load.
Nobody needs more bio-load, not from a feeder at least.
..................................................................................................................................
I would never recommend a LFS/LPS Goldfish or Rosey Red as feeder, for the facts that they are higher in fats and the thiaminase.
When I do suggest feeders, they are tropicals, e.g. Guppies, Platies, Cons, and other inexpensive or easily bred tropicals.
These are also not commonly kept as in the same deplorable conditions as standard feeders, conditions which breed the disease/parasitic infestations all too common in LFS feeders.
Any fish from the LFS/LPS requires a thorough quarantine before introduction to our beloved display fish/tank(s).
A good quarantine involves not just time spent under observation(A month is generally adequate IMO/IME), but direct treatment aimed at the most common problems, e.g. ICH and internal/external bacterial/parasitic infestations.
Even if you raise the Goldie or Rosie yourself and know they are as healthy as can be, I still wouldn't feed'em due to the fat and thiaminase.
Just too many easy to buy/raise tropicals that are much better suited as feeders for other tropicals.
Just my $0.02, HTH.
