Feeder Fish Mini-faq: The Pros And Cons

ArauraDiscus

Fish Addict
Joined
Jun 15, 2007
Messages
875
Reaction score
0
Location
Maryland U.S.A
You do know that in the second and third levels of carnivorous fish, you have Ctepnoma, and Leafish respectively, but both are the same thing...


Very informative though, good read.
 

jayjay

The BE-Team Fighting For Betta Extermination
Joined
Apr 12, 2006
Messages
3,665
Reaction score
0
Location
Gloucester, England
You do know that in the second and third levels of carnivorous fish, you have Ctepnoma, and Leafish respectively, but both are the same thing...


Very informative though, good read.

Ctepnoma spp. are different from leaf fish (Monocirrhus polyacanthus), they aren't the same thing.
 
OP
nmonks

nmonks

A stroke of the brush does not guarantee art from
Joined
Jul 16, 2005
Messages
5,803
Reaction score
5
Location
Berkhamsted, Hertfordshire, England
Indeed. The problem of using common names! If we all used Latin names instead life would be *so* much easier! :hey:

The name "leaf fish" and "leaffish" are used for a whole bunch of different species according to Fishbase. Pretty well anything small, brown, and pretending to be a dead leaf has ended up with the name at some time or another.

Cheers, Neale

You do know that in the second and third levels of carnivorous fish, you have Ctepnoma, and Leafish respectively, but both are the same thing...
Ctepnoma spp. are different from leaf fish (Monocirrhus polyacanthus), they aren't the same thing.
 

sryan0609

Fish Fanatic
Joined
Jan 12, 2009
Messages
187
Reaction score
0
Location
Loveland, Cincinnati, Ohio, USA
Most aquarium fish are carnivores, though their prey is usually small crustaceans and insects. Such fish are easily maintained on live or frozen substitutes such as mosquito larvae, bloodworms, brine shrimps, daphnia, and so on. Many will also take flake foods and pellets, which are often more convenient and are certainly inexpensive and nutritious.

However, some aquarium fish are piscivores, carnivores that will catch and eat other fishes. These can be broadly be divided into three groups:

1. Species that are opportunistic piscivores, that is, only eat smaller fish if the opportunity presents itself; otherwise, they have evolved to feed primarily on other prey items. Angelfish fall into this category; while they have evolved to eat mosquito larvae, they will certainly eat very small fish such as neons and livebearer fry, given the chance. Other opportunistic piscivores include archerfish, small catfish such as Pimelodus pictus, and most of the larger tetras and barbs.

2. Species that are facultitive piscivores, that is, while they have evolved to catch and eat small fish, they also eat a variety of other small animals as well. They are therefore easily adapted to alternative diets in aquaria. Ctenopoma, bichirs, needlefish, oscars, gars, and most of the predatory catfish and pufferfish fit into this category. In the wild they eat a wide variety of prey items besides fishes, and in aquaria readily take things like prawns, earthworms, bloodworms, mussels, and other meaty foods. Many will also take frozen whitebait and lancefish as well.

3. Species that are obligate predators, that is, they have evolved to feed more or less exclusively on smaller fish and are difficult or impossible to adapt to an alternative diet. Species in this category include leaffish, needlefish, pike livebearers, prehistoric monster fish, and freshwater stonefish.

The ADVANTAGES of feeding live fish

The prime advantage (from a practical point of view) is that feeding live fish to a piscivorous fish simplifies the maintenance of otherwise difficult species. Weaning an obligate piscivore onto dead foods is time consuming and to some extent depends on starving the fish in question. If that fish is newly imported, it might not have eaten a proper meal in weeks, in which case further starving it may weaken the fish, even kill it.

A problem with the most reliable alternative live foods, things like earthworms and river shrimp, is that obtaining them can be difficult and supplies often seasonal. By contrast, most aquarium shops routinely hold stocks of small fishes like goldfish and guppies, and given piscivores often only need to eat every few days, buying cheap fish is not very expensive.

Some aquarists also believe that live fish offer the best diet for piscivorous fish. This is not necessarily true if only one type of fish is used (see Best Practise below) but in theory at least, a live fish diet should be a reasonable match for what a piscivorous fish eats in the wild. Using a substitute that a species would not encounter in the wild (like brine shrimps or squid) might not provide the full balance of nutrients that it needs.

Finally, a few aquarists also hold that live fish provide piscivorous fish with stimulation otherwise lacking in the aquarium.

The DISADVANTAGES of feeding live fish

The main disadvantage of using live fish as food is the risk of introducing parasites and bacteria into the aquarium. Cheap, mass produced fish, especially goldfish, are maintained in squalid conditions. Mortality, even when these fish are kept as pets, is high. While one goldfish might only pose a small risk to a predator, the risk is cumulative over time. So if you feed a predatory fish a goldfish once every two or three days, even after only a few months the chance of infecting your pet fish with something nasty is virtually a certainty.

A second disadvantage is nutritional imbalance. Goldfish in particular are fatty and are not a healthy staple diet for most piscivorous fish. In the wild, piscivorous fishes will take a wide range of species, some herbivorous, others smaller predators. This means that the piscivorous fish will be able to obtain a correspondingly wide range of nutrients. Simply feeding one species of feeder fish is both unnatural and very likely unhealthy. This problem can, to a degree, be mitigated by "gut loading" feeder fish (see Best Practise, below). By contrast, flake and pellet foods have been carefully formulated to provide a perfect diet for fish. While it might seem monotonous to us, these prepared foods are actually the best all-round diet for most fish.

A third disadvantage is that some feeder fish (notably goldfish and rosy-red minnows) contain large amounts of the enzyme thiaminase. This breaks down thiamin (vitamin B1) and over time this will lead to serious health problems.

The ETHICS of feeding live fish

Use of feeder fish divides the aquarium hobby sharply. The majority of aquarists disapprove of the practise, and most fishkeeping books and magazines recommend against it. Essentially, the argument boils down to whether or not it is cruel. On the one hand, the advocates of feeder fish usage maintain that the prey fish is killed quickly, and that killing a small fish is no different from killing an earthworm, river shrimp, or any other small animal. Since most aquarium fish foods are based at least in part on animal protein (often fishmeal) even flake food has, at some point, involved the death of fish.

On the other hand, opponents hold that it is largely unnecessary, and that we cannot know if a prey fish swallowed by a larger fish dies slowly or quickly. Moreover, in many instaces death clearly does not come quickly, where the prey fish is dismembered by one or more predatory fish. Irrespective of how quickly the fish is killed, simply being dumped into a strange aquarium and then pursued by a predatory fish must be intensely stressful.

Another argument is that feeding live fish to a predator fish is simply doing what happens in Nature, so questions of cruelty are irrelevant. Opponents point out that "the wild" is a big place, and prey fish usually manage to escape predators by swimming away to safety. Under natural circumstances, predatory fish only very rarely make a kill, and often have to go days or weeks without food. Therefore, simply dumping a couple of goldfish into a small aquarium doesn't in any way mimic Nature.

A third argument concerns the degree to which fish feel pain. For many years it has been assumed fish do not feel pain. This is because they lack the same type of pain receptors that we (and other higher vertebrates) have. In recent years, however, the evidence has begun to swing the argument in the other direction, with scientists now believing that fish do feel pain. Fish will, for example, avoid using injured parts of their body, in just the same way as we won't put our weight on a twisted ankle.

Ultimately, the ethical arguments come down to a simple fact: Some people enjoy watching their predatory fish exhibiting their predatory behaviours. Others do not. Very few predatory species cannot, eventually, be adapted to alternative foods, and those species are rare in the hobby. The vast majority of predatory fishes kept by aquarists (things like oscars and catfish) don't need live feeder fish, but will eat them if you provide them. The choice is yours.

Best Practise

If you do want to use live feeder fish, then the first thing to do is find a way to avoid introducing parasites. Probably the best approach is to use livebearers that you can breed yourself, such as mollies and guppies. While some people have also used cichlid fry as feeders, the spiny fins on these fish are problematic for many predators not especially adapted to deal with them. Livebearers, by contrast, are small and soft, and won't choke your prize predator.

Goldfish and rosy red minnows can be easy to breed, but they suffer from being high in the chemical thiaminase. They must not be used as the staple diet, because over time they will prevent the predatory fish from having enough vitamin B1, which will cause serious health problems. The muscles, bones, and nerves appear to be most seriously affected.

Using cheap fish from your local pet shop is a poor alternative; by any objective standard the risks are high. Quarantining and treating feeder fish with anti-parasite and anti-bacteria drugs may be an option, but if you aren't prepared to do this, you would be wise to pass over this source of feeder fish.

The other key advantage of raising your own feeder fish is that you can "gut load" them. Predatory animals, even strict carnivores like cats, depend upon the gut contents (usually plant matter) of the prey animals they eat to obtain certain nutrients lacking in meat. This is why cats eat the guts and liver of mice and birds they catch, yet ignore the bits that seem nicer to us, like the wing muscles. Likewise, predatory fish will benefit from being fed feeder fish that have themselves been fed properly. Make sure that the feeder fish have been fed vitamin-ennriched food before they are offered to the predatory fish. Vegetarian and algae-based foods are generally considered the most useful. The feeder fish should be "fattened up" for anything up to a month before being used.

When using feeder fish, only add as many as will be eaten within a few minutes. Ideally, feed just one, and only add another if the predatory fish is still obviously hungry. What you want to avoid is having a bunch of terrified, battered fish swimming about the tank. If nothing else, they will be placing an additional strain on the filter as well as using up oxygen.

Finally, treat the feeders with respect. Use feeder fish of suitable size that they will be killed quickly. Don't contrive cruel situations where the prey animal dies by inches. If you are going to use feeder fish, at least do so intelligently and for the good of the fish you are keeping, not merely for the fun of watching one animal kill another.

so all together what would you advise me to feed my 8 red belly piranhas? i feed my reds too many feeder comets and im stopping that right now, i also feed them beef heart, and krill.

i feed them way to many feeder fish now, my reds seems fine, but how do i know if my reds are healthy?

also can i just buy frozen fish from a store and thaw them out and give em to my reds?
 
OP
nmonks

nmonks

A stroke of the brush does not guarantee art from
Joined
Jul 16, 2005
Messages
5,803
Reaction score
5
Location
Berkhamsted, Hertfordshire, England
so all together what would you advise me to feed my 8 red belly piranhas?
In terms of safety, practicality, and cost, the answer to this is yes, it is always better to feed dead foods than live feeder fish. If your fish will accept dead food, and almost all will, then you will find feeding them dead food altogether better than live feeder fish.
i feed them way to many feeder fish now, my reds seems fine, but how do i know if my reds are healthy?
The problem with the fat- and thiaminase-issues are that they are cumulative. Like any nutritional imbalance, things might be fine for a long time, but after months or even years of the wrong foods, then things go wrong. Typically fish that are fed too much fat are basically okay but die many years prematurely, and it is only an autopsy that reveals the problem. To the casual aquarist, it seems the fish was fine except for the fact it suddenly died!
also can i just buy frozen fish from a store and thaw them out and give em to my reds?
Yes. Most shops should sell small frozen fish such as lancefish. Small specimens will take invertebrates like bloodworms, while larger specimens happily accept earthworms, river shrimps and so on. Chunky seafood is also useful, but do review that article on thiaminase posted elsewhere on this sub-forum; in particular, prawns and mussels shouldn't be used too frequently because they are rich in thiaminase. Piranhas will accept a very wide range of foods, including dried fruit/seed mixes sold for canaries! Apparently an important part of their diet in the wild; isn't it funny how lots of piranha keepers are desperate to feed them live mice because they've read they eat mammals, and yet so few of them also make the effort to match the vegetarian part of their diet? Anyway, there's a good literature on feeding piranhas, and I'd encourage you to have a read. Since wild fish are opportunistic, they'll really eat just about anything.

Cheers, Neale
 

Xenon Junkie

Fish Fanatic
Joined
Jul 13, 2009
Messages
135
Reaction score
0
Location
Northampton, England
Not to revive anything but,
isnt the feeding of any vertibrate animal whih is alive, illegal under the RSPCA's Cruelty to animals law?
Please correct me if im wrong, i've used feedfish myself but this statement i got taught in my Exotic Animal care course grabbed my attention.
 

swaddell13

New Member
Joined
Jul 15, 2009
Messages
50
Reaction score
0
Location
Chandler, Arizona
nice post neale! I had no idea that there where liverbearers that where carnivors... the pike livebearer looks like it has a beak to chomp on other fishies!


see? haha
 

Missing Score

New Member
Joined
Aug 27, 2012
Messages
8
Reaction score
0
I'm not sure if this has been mentioned yet but feeding live fish is now illegal in the UK I think. Interesting article on it:

http://www.practicalfishkeeping.co.uk/content.php?sid=3713
 

Unicron

New Member
Joined
Jan 7, 2013
Messages
1
Reaction score
0
Location
Montreal, Quebec
I have a giant snakehead who refuses to eat pellets. Iv tried and he wont budge, i once got him to eat sausage that we made but i know red meat is bad for fish. SO for now im stuck feeding him 2 live goldfish every 2 days. What I was wondering is that since the fish I feed my snakehead do eat the massivore pellets i feed them while in the QT tank, would the nutrients they ingest from the food not be transmitted to my snakehead?
 

trending

Most reactions - Past 7 days

Top