Nutrition

The problem

Most crab feed sold in India is shrimp feed wearing a different label, and the two animals do not eat the same way at all. A shrimp finds a pellet and finishes it. A mud crab takes food in its chelae and picks at it, slowly, sometimes for an hour.

A pellet engineered for a fast feeder has already softened and broken apart by then. It leaves the crab still hungry and hands the difference to your biofilter as ammonia. You pay for that feed twice — once at purchase, and again in water quality.

What it does

CRUSTA is formulated for a slow feeder. Sinking pellet, 47% crude protein, and water stability held long enough for a crab to actually finish what it picked up — with an attractant profile mud crab responds to, because a feed the animal ignores is not a cheap feed.

One animal, four nutritional problems

A crablet, a crab being fattened for market, an animal being pushed through a moult, and a female being brought into berry are not the same feeding job. Different protein, different lipid, different mineral load — and a different pellet size, because a pellet the animal cannot handle is wasted no matter what is in it.

So CRUSTA is a range, not a bag.

The problem

Mud crab is a brackish-water animal. It needs a specific salinity, and more than that, it needs the ionic profile that comes with real estuarine water — calcium, magnesium, potassium in the right ratios, not just salt.

Most inland farms do not have that. They have borewell water, or municipal water, or fresh water from a canal. Adding common salt raises the ppt reading and does almost nothing for the animal, because the ions it actually needs are still missing. The crab survives, badly, and the farmer cannot work out why growth is poor.

What it does

CrabShield Complete is a mineral salt mix that dissolves directly in the tank and rebuilds the full brackish-water profile at the ppt mud crab culture needs. Not a salinity correction — a water build. You can run a crab system a long way from the coast on it.

The formulation is not a generic salt blend with the ratios guessed at. It is derived from two things directly: the mineral profile of the mud crab itself, and the profile of the estuarine water it evolved in. The animal and its habitat tell you what the mix has to be — we read it off them rather than off a shrimp datasheet.

The problem

In a closed system, alkalinity falls. Nitrification consumes carbonate every day, and the moulting crab draws on it too — a new shell is built out of it. Once alkalinity drops, pH stops holding steady, the biofilter slows down, and moults start failing.

Farmers usually catch this late, when animals are already stuck mid-moult. And the general-purpose alkalinity products on the market are written for shrimp or fish, at bands that were never worked out for a crab.

What it does

CrabShield Stabilizer holds alkalinity inside a range we standardised ourselves, on Scylla serrata, in our own systems. It is a mud crab number, not a borrowed one. Dosed routinely, it keeps the buffer where the moult needs it and stops the slow drift that quietly costs a cycle.

Like Complete, it is built off the mineral profile of the animal and its natural environment — so what you are holding the water at is what the crab would have found in the estuary, not a number that happened to work for a different species.

The problem

A closed system is a bacterial system. The biofilter is bacteria doing useful work, and most of what goes wrong is bacteria doing something else — opportunists moving in when organics spike after a heavy feed, a mortality, or a grading day.

You cannot sterilise your way out of it. Remove the bacteria and you remove the biofilter. The only thing you can do is decide which population is dominant.

What it does

A Bacillus culture conditioner that keeps the beneficial population on top through the load peaks — competing for the same substrate the opportunists want, and giving the system somewhere to put organic waste other than into the water your crab is sitting in.

What makes it different

Almost every probiotic sold into Indian aquaculture is a generic strain off a shelf — a culture pulled from a collection, or from a shrimp pond, that was never asked whether it can live on a crab. It arrives in your tank as a stranger and often behaves like one.

Ours were isolated from healthy mud crab. The strains in this bottle came out of the animal itself — from crabs that were thriving, in the conditions we culture in. They are not visitors to the system. They are the population a healthy crab already carries, put back at a dose that lets it stay dominant.

The strains in it were isolated from healthy mud crab — from the animal itself, not bought off a catalogue. That difference decides whether a probiotic works or just costs money. An off-the-shelf strain has to survive an environment it never evolved in and outcompete organisms already adapted to it; most of it washes out within days of dosing.

A strain taken from a healthy crab is already home. It colonises, it holds, and it keeps working after you stop watching.

The story

Think about where your crabs come from. They are collected at a landing centre or from a collection agent, tied, packed into baskets or crates, and loaded into a vehicle. Then they travel — six hours, twelve, sometimes longer, often through the heat of the day, often stacked, dry or in damp gunny, with no water moving over their gills.

By the time that crate reaches your farm the animal inside has been out of its environment for most of a day. It is dehydrated. Its gills are loaded. Its haemolymph chemistry has shifted, and its immune response is already spent on the journey. It looks fine. It is not.

Drop that animal straight into a fresh RAS tank and you add one more shock on top of everything else. This is why so many farmers lose animals in the first seventy-two hours after stocking and end up blaming their system, their water or their seed supplier — when the loss was booked on the road, before the crab ever arrived.

What it does

CrabCare is a short herbal immersion given before the crab enters the system. It brings the animal down off transport shock, supports the stress response, and lets it enter the tank in a state where it will actually settle and feed instead of spending its reserves on recovery.

It is the cheapest intervention on this page and usually the one that changes a farmer’s numbers first.

The problem

Powdered minerals have to dissolve before they can do anything. In a working tank that takes time — and some of it never dissolves at all, it settles on the floor as a cost you paid for and the animal never received.

The moment minerals matter most is the moment you have the least time. A crab that has just shed its shell needs calcium and the rest of the mineral load now, in the hours when the new shell is still soft and it is defenceless. A powder that is still dissolving is not delivering.

What it does

AquaShield is a liquid mineral — the first in India formulated in liquid form for crab culture. It is already in solution when it hits the water, so uptake starts immediately instead of after a dissolution lag. Same minerals, delivered on the timescale the animal actually works on.

Use it as the fast intervention alongside routine powder dosing: through moult windows, after handling and grading, and whenever a batch needs mineral support in hours rather than days.