|  | Natural Feeding Method |  | | | | | From the very beginning of the captive care of marine animals within home, public
and research aquariums to the present day, we have been feeding the animals
contained in such systems incorrectly. This method of feeding results in many
problems associated with the long term care of animals within a marine aquarium.
It is not the total amount of food that is the problem, which has previously been
accepted in the past and blamed for poor water quality, but the manor in which it is
delivered that causes adverse effects on the livestock and system.
We came to this startling conclusion after Dr Ellen Thallers presentation at the
WYMAG seminar October 2002, and the installation of a new and revolutionary
feeding system in a marine aquarium, with outstanding results.
Dr Thaller described reef fish eating plankton at a rate of 50 -60 pieces per minute all
day. She then spoke of a food injection system in her research aquariums providing
small quantities of small particle food continuously during the day light hours. Her
results found a dramatic reduction in aggression between fish species and an increase
in vitality and health.
We decided to develop this feeding practise and alter the food delivered and time
scale to see the effects on a large system stocked with fish, motile and sessile
invertebrates with a 98% hard coral stock.
We wanted to see the effects of continuous feeding in the aquarium but not solely
aimed at the fish. We developed Dr Thallers idea from feeding fish in the daylight
hours to feeding continuously injecting not only fish food but coral food as well, with
food injection 24 hours a day to facillate the nocturnal feeding of some coral polyps,
other sessile filter feeders and mobile invertebrates such as crabs and shrimp species.
We also introduced a new food source to the aquarium, live phytoplankton, the oceans
primary producers to increase the zooplankton population, in an effort to develop a
more natural food source.
In other words we are feeding the aquarium 24 hours a day 7 days per week.
We looked at the effects of this food injection not only on the animals which we were
targeting but also the natural population of life within the aquarium system. We also
had to monitor the effects of this feeding on the filtration and water quality of the
system.
With traditional feeding at two to three times per day and no nocturnal feeding the
natural feeding patterns of our small reef fish, corals and other animals are altered,
this has many detrimental effects on the animal, filtration system and it’s operation.
The effects of this feeding are vast, animals that have evolved to have a low
concentration of food but continuously supplied are suddenly subjected to a gorge,
starvation, gorge, starvation feeding regime.
This sporadic introduction of relatively large amounts of food causes many problems.
1. Fish gorge themselves to collect as much nutrition as possible in a short time
span, filling the gut with large unnatural amounts of food.
2. Large amounts of food remains partially or undigested within the fish gut and
is passed as faeces, only a small proportion of food is assimulated through the gut
wall. This represents a huge loss in the animals potential energy budget and an
increase in contamination to the aquariums water body.
3. The animals are then starved with only natural food to eat existing at a very
low concentration. Over time the fishes health can suffer as they begin long term
malnutrition. This results in a loss of vitality, high rate of disease, infection, and a
high mortality rate.
4. Fish behaviour is altered as they become unnaturally aggressive to species
they would ignore in their natural environment.
5. Large amounts of microscopic particulate food is lost to the system, most will
reside in the boundary layer existing over the solid/ liquid interface of the rockwork
within the aquarium. If not eaten by scavengers this then can rot down causing
pollution and possible algal problems.
6. Filter feeding foods are often added in too small amounts once per day,
resulting in rapid increase and rapid decrease in food concentration to the animals.
7. Corals and other Cnidarians suffer as their food source is sporadic. A surge in
amino acids stimulate their feeding responses but is often to late as the main bulk of
particulate food has been taken out of the system by filtration, or eaten by other
animals, by the time the corals have extended their polyps to feed.
8. No food is added during the night, many animals including corals and other
filter feeders are active during the night. They rely in the capture of natural nocturnal
zooplankton within the aquarium, whose populations remain low due to low food
source and predation. Nocturnal feeders are slowly starved.
9. For Cnidarians less food is assimilated, resulting in less waste production, this
waste is food for the symbiotic algal population within the gut wall, this results in a
lower algal population within the coral, resulting in low algal waste such as sugars
required by the coral as food.
10. Lower algal activity results in lower growth rates of the corals, and lower
calcification in the growth of hard corals.
11. Again long term malnutrition acts upon the animals resulting in weaker
animals which lowers the vitality, and increases the disease and mortality rate.
12. Denitrifying bacteria populations and activity fall and rise to the availability of
their food source, this source again has high peaks and low troughs due to the feeding.
As a surge in toxins appears the bacteria are slow to respond, this results in a high
residence time of toxins in the system. Even at low concentrations the toxins are
acting on the metabolic processes of the aquarium inhabitants further increasing the
biological stress levels.
So it follows that if we can feed our captive animals in a way in which they have
evolved to feed, this would result in healthier animals, higher growth rate, less disease
and mortality.
What we had to do was devise a way in which we could provide food for all the
animals within the system as close to their natural requirements. Whilst increasing the
food quantity yet not suffering a drop in any water parameter, thus maintaining high
water quality.
The Aquarium, Filtration System and Stock
The aquarium is owned and extensively maintained by Mr Mark Howarth, in the
North West of England who Co-authored this report..
The Aquarium system has a water capacity of 7,000l and has been in operation for 8
months, however the filtration system is 2 years old. The aquarium has over 1200kg
of live rock, over 100 fish ranging from a 20cm naso tang, Naso lituratus to a shoal
of ventralis anthias, Pesudanthias ventralis 2.5cm long, around 300 hard corals about
200 small polyped stoney corals and 100 large polyped stoney corals, anemones,
gorgonians, worms and countless crabs and shrimps.
The aquarium is lit by 7 x 400w 10,000K metal halide luminaries and a custom built
light computer by Aqua-Medic and 5 x D & D Aquarium Solutions T5 pendant units
each with 6 x 39w Actinic tubes , with a moonlight all under computer control. All
lamps are from Arcadia. Water circulation is via 12 x IKS turbo 3500 pumps with a
40% reduction in power during the night.
Temperature is controlled via a plate heat exchanger, air conditioned aquarium room
and a chillier.
The filtration consists of an Aqua-Medic denitrafication unit, Deltec fluidised bed,
calcium reactors x 2 running 12 hours per day turned off during the night, injection of
ozone only when the redox potential fall below 450, and is very rarely used. Deltec
AP1006 protein skimmer with a self cleaning head, algal refugium reverse lit with a
150w hetal halide, phosphate control via a Deltec fluidised bed Rowaphos reactor,
and a Deltec Kalkwasser stirrer, doseing at night only. UV sterlisation is not used.
Iodine, strontium, and various trace elements by HW Aquaristic are dosed under
computer control every 4 hours. Salinity is kept constant with an automatic top up
system, and 20% water changes using HW synthetic marine salts are performed once
per month. Total water turnover is at the rate of 64,000 litres per hour.
All water parameters in both the sump and main aquarium are monitored via two IKS
proffesional computer systems with the general parameters at the beginning of the
feeding being :-
Salinity 1.026, Temp 26 celcius, pH 8.2 -8.4, Calcium 420ppm, DKH 8, Alkalinity
3.3, Magnesium 1420ppm, Iodine 0.06, Nitrate 20ppm, phosphate nitrite and
ammonia 0.0 Redox potential 450
Feeding
As we wanted to feed during the night time hours, after much discussion we decided
to increase the total food given to the aquarium. We had also decided to add a totally
new food source, live phytoplankton to the system in an effort to increase the natural
zooplankton population, facilitating another increase in food injected to the system.
The existing feeding was as follows:-
All food listed here was the total food injected to the system in a 24 hour period, fed
twice per day half in the morning the other half in the evening.
1 blister pack of San Franscio Bay Baby brine shrimp
1 blister pack of Aquafresh Cyclops
16 cubes of Gamma Omega 3 enriched brine shrimp
8 cubes of Gamma Mysis shrimp
4 cubes of Aquafresh chopped cockle
4 cubes of San Franscio bay chopped mussel
5 ml HW Multi Vitiamin Complex
400ml of Marine Snow or Marine de lux alternating daily
Sanfranciso bay Seaweed Salad, green marine algae, 3 full sheets per day.
We decided to mix up a two day supply of food in a container for the contionus
feeding, the following were mixed together:-
500 ml Marine Snow
500 ml Marine Deluxe
1 blister pack of San Franscio Bay Baby brine shrimp
1 blister pack of Aquafresh Cyclops
12 cubes of Gamma Omega 3 enriched brine shrimp
10 ml HW Multi Vitiamin Complex
Then diluted with aquarium water to a volume of 2 litres.
This represented an increase of food by 200ml of coral food and mixing the two
brands together as previously they had been fed on alternating days,Twice a day
the following was added to feed the larger fish in the aquarium:-
4 cubes of Gamma Omega 3 enriched brine shrimp
8 cubes of Gamma Mysis shrimp
4 cubes of Aquafresh chopped cockle
4 cubes of San Franscio bay chopped mussel
This represented an increase of 4 cubes of brine shrimp,The dried seaweed
feeding remained unchanged.
4 liters of home cultured phytoplankton Nannochloropsis oculata over a 24 hour
period, This was a totally new food source to the aquarium.
The Continuous Feeder
Equipment :-
Aqua-Medic plankton reactor and peristaltic pump
Air volution 2 air pump and air line
IKS Aquastar computer and 4 plug bar non variable
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| Method
The food was placed into the plankton reactor and then the reactor was filled with
aquarium water. The air pump was connected to the plankton reactor and air passed to
mix and suspend the food mix within the reactor. Air line was passed to the base of
the reactor with a bend at the bottom to avoid the stream of bubbles from the air inlet
without any kink in the pipe. This air line was connected to the suction side of the
peristaltic pump. Air line was connected to the pressure side of the pump and passed
to the aquarium terminating above the outlet of an IKS turbo pump to ensure dispersal
of food on introduction to the system. The pump was plugged into the IKS plug bar
and the IKS computer programmed to switch on the pump every 15 minutes for 5
seconds 24 hours a day, 365 days per year.
This timing allowed the peristaltic pump to deliver 20ml of food solution to the
aquarium system every 15 minutes.
The remaining frozen food described was thawed in a glass of aquarium water and
released into the aquarium in bulk twice per day. The seaweed was fixed to the side of
the aquarium using a lettuce clip three times per day.
Phytoplankton Feeding
Equipment:-
Cleartides fluidised bed filter
Air-volution 4 air pump, air line, 5mm ridged piping and air stone
Twin 54w Arcadia T5 starter and marine white tubes and reflectors.
Plankton culture and nutrients.
Salt water.
Peristaltic pump and digital timer.
One 2 meter high 15 cm diameter clear tides fluidised bed filter was modified by
cutting down the centre pipe to a length of 30 cm. A standard air stone was attached to
the end of a 5 mm ridged pipe was passed down to 10 cm from the bottom of the
reactor in the middle of the cut down centre tube, and the air pump turned on. The
reactor was filled with a fresh salt mix with a specific gravity of 1.026 at 26 celicus.
The T5 tubes and reflectors were fixed at opposite sides of the reactor and timed for
18 hours per day. 500ml of culture was added and fed with nutrients until dark
uniform green culture was produced.
Air line was fed into the reactor and attached to the peristaltic pump, the terminal end
of the air line from the pressure side was placed in front of the suction intake of the
main return pump from the sump to the aquarium. The peristaltic pump was timed to
deliver 333 ml of live phytoplankton over a twenty minute time span every 2 hours 24
hours per day.
The phytoplankton culture was topped up every day with fresh salt water mix and fed
nutrients, we are currently looking to install a further 3 reactors to ensure an even
culture density at all times, whilst reducing the nutrient content within the culture.
Results after 28 days of continuous food injection
Water Quality improved even with the increase of food injected to the system all
levels remained stable at the levels before the feeding commenced, only the nitrate
level fell from 20ppm to 5ppm in 28 days.
There was no evidence of an increase in element depletion within the water body as
expected with the increase in coral growth. We did not have to change any settings on
the reactors within the system, or any dosing rates altered.
Big increase in calcareous algal growth over the rockwork, aquatic equipment and
glass was noted, with a distinct improvement in pigmentation.
A zooplankton population explosion, with a consertive estimate being at over 500%
biomass increase within the aquarium and sump filter.
Dramatic increase in coral coloration, polyp extension and growth rates, it is
estimated that hard coral growth from the beginning of the feeding exceeded the
growth for last three previous months.
Distinct drop in fish aggression between established fish with new additions hardly
recognised.
Discussion
We stress that we have no quantative data on the change apparent however we can
provide a theory with sound evidence to warrant on going experiments to collect such
data. We also acknowledge that the time span is far to short to establish longterm
success but felt we had to release the study because of the magnitude of change
involved. Much is still to be done and too much remains unknown, it is with this in
mind we ask fellow aquarists not to attempt this on their home aquariums for the
longterm effects could prove to be negative.
We increased the total food injected to the system, yet reduced the daytime feeding
quantity resulting in less food available to the fish, corals and daylight feeders, and
injected a relatively high density of food to the nocturnal feeding animals within the
system. Low quantities of food released contiounsly into the system allowed the fish,
corals and other animals to consume small particles but regularly, resulted in the
following theory:-.
1. Nutrition assimulation through the gut is at a constant allowing an unchecked
supply of energy.
2. Digestive enzymes levels within the gut remain constant to the food supply
allowing a greater digestive ability to attack the food as it is passed through the gut,
resulting in a more efficient nutrient assimulation less waste produced and released to
the system.
3. Less food is lost as particulate waste as the fishes feeding behaviour changes
from biting and fighting, to passively picking at pieces which can be swallowed whole
and not bitten which release particles to the system.
4. We are hoping to show a drop in disease and mortality rate due to the increase
of vitality within the fish and coral stock.
5. Corals and other Cnidarians are subject to a constant but low level of free
amino acids 24 hours per day, this stimulation ensures a high degree of polyp
extension facilitating a higher rate of prey capture.
6. The constant and higher supply of nutrients results in a steady rate of waste
produced allowing the symbiotic algal populations to remain constant and at a higher
density due to the increase in the supply of food.
7. This enhanced algal activity and nutrient concentration results in a greater
growth rate of the coral.
8. There is less waste produced in the system, but what degree of waste there is
remains at a much more constant level. This allows the denitrifying bacterial
population and activity to remain constant to the food supply, resulting in a much
lower toxin residence time within the aquarium water body. Therefore less stress is
exerted on the biological functions of the animals.
9. The introduction of live phytoplankton acting in a synergistic manor with the
new feeding during the night has boosted the natural planktonic populations within
the aquarium. Most zooplankton species are nocturnal rising in the water column to
filter phytoplankton or prey on those that do. The nocturnal feeding allowed a higher
food source to the planktonic filter feeders facilitating a population explosion, the
predatory zooplankton population followed. The constant supply of food allowed the
predator prey populations to remain at a higher and dynamic level, we hope to sustain
this level if not increase it, however too higher levels may prove detrimental to the
system..
!0. This increase in plankton biomass represents a huge increase in the natural
food source of nocturnal filter feeders as many species of small polyped stoney corals
are. Higher concentration and natural food source for these corals results in increased
growth and vitality.
11. Other sessile filter feeding animals such as sponge, bryozoan and tunicate
populations increase providing increased water purification and natural food source
for others.
12. The motile benthic invertebrate population also exploded allowing a greater
turnover of the sediment. Resulting in a cleaner substrate as detritus is formed and
consumed at a constant rate, further reducing toxic waste production.
13. The increase in hard coral growth and calcium fixation rates within the system
has not forced us to alter the calcium production rate from the calcium reactors, or
have we had to alter any element dosing rates. We feel this is a direct result in the
increase of zooplankton predation providing those natural elements in a more natural
form. Elements utlised and removed from the water body via biological pathways
must come from somewhere, and we may well have to alter the dosing rates to
maintain levels in the future. However the increase in benthic biomass and activity
will provide an increase in acidic secretions acting on the surface of the calcareous
substrate. This will provide an increased source of calcium and other elements to the
aquarium water body, and may be contributing to balancing the increased demand.
14. We have achieved a nitrate level drop of 15 ppm yet we have increased the
food levels introduced to the aquarium. High nitrate levels have mostly been
associated with over feeding and high levels of waste. Even though we increased the
food concentration we spread it over time, this resulted in more food being
assimulated and thus less waste produced. Less food was lost as detritus and the
detritus that was created soon became consumed by the natural populations of
scavengers, only to recycle up the food chain within the aquarium, and not rot down.
The introduction of live phytoplankton may also be responsible utilising nitrates as a
food source.
With the cessation of starve/gorge feeding replaced with constant release of food into
the system over 24 hours per day and a new food source, the base of the natural
aquatic food web, phytoplankton, a dramatic change has occurred to all life within the
closed system. The problems associated with traditional feeding as previously
discussed are dampened and every aspect of life within the aquarium is altered
showing dramatic change in population dynamics within the planktonic, benthic,
sessile and motile invertebrates. Hard coral growth, coloration and polyp extension
increases, the fish are less aggressive and coloration has increased.
We have introduced 5 Dendronephthya species, a coral acknowledged to be
impossible to keep in aquariums, to see if this new method of feeding will allow them
to not only survive but grow in captivity.
To sum up we feel that this method of feeding allows energy to be transferred more
efficiently through each and every pathway of the food web within the aquarium,
resulting in an increase in the health of animals contained within it. Less biological
waste produced as a result improves the water quality exerting less biological stress
on the animals and a more efficient denitrifying bacterial population.
This short study may well prove to be further evidence that striving to create a near as
natural environment for marine animals housed in a closed system is the way forward
to increasing our success in the husbandry of such creatures.
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